Closed loop feedback control of motor velocity of a surgical stapling and cutting instrument based on measured time over a specified number of shaft rotations

ABSTRACT

A motorized surgical instrument is disclosed. The surgical instrument includes a displacement member configured to translate over a plurality of predefined zones. A motor comprising a shaft is coupled to the displacement member. A control circuit is coupled to the motor. A position sensor is coupled to the control circuit to monitor the rotation of the shaft. A timer circuit is coupled to the control circuit. The control circuit is configured to receive rotations of the shaft in a current zone defined by a set rotation interval, measure time at a set position of the rotation interval, wherein the measured time is defined as the time taken by the displacement member to traverse the rotation interval based on a predetermined number of shaft rotations, and set a command velocity of the displacement member for a subsequent zone based on the measured time in the current predefined zone.

TECHNICAL FIELD

The present disclosure relates to surgical instruments and, in various circumstances, to surgical stapling and cutting instruments and staple cartridges therefor that are designed to staple and cut tissue.

BACKGROUND

In a motorized surgical stapling and cutting instrument it may be useful to control the velocity of a cutting member or to control the articulation velocity of an end effector. Velocity of a displacement member may be determined by measuring elapsed time at predetermined position intervals of the displacement member or measuring the position of the displacement member at predetermined time intervals. The control may be open loop or closed loop. Such measurements may be useful to evaluate tissue conditions such as tissue thickness and adjust the velocity of the cutting member during a firing stroke to account for the tissue conditions. Tissue thickness may be determined by comparing expected velocity of the cutting member to the actual velocity of the cutting member. In some situations, it may be useful to articulate the end effector at a constant articulation velocity. In other situations, it may be useful to drive the end effector at a different articulation velocity than a default articulation velocity at one or more regions within a sweep range of the end effector.

During use of a motorized surgical stapling and cutting instrument it is possible that the velocity of the cutting member or the firing member may need to be measured and adjusted to compensate for tissue conditions. In thick tissue the velocity may be decreased to lower the force to fire experienced by the cutting member or firing member if the force to fire experienced by the cutting member or firing member is greater than a threshold force. In thin tissue the velocity may be increased if the force to fire experienced by the cutting member or firing member is less than a threshold. Therefore, it may be desirable to provide a closed loop feedback system that measures and adjusts the velocity of the cutting member or firing member based on a measurement of time over a specified number of shaft rotations. It may be desirable to measure the number of shaft rotations at a fixed time.

SUMMARY

In one aspect, the present disclosure provides a surgical instrument. The surgical instrument, comprising a displacement member configured to translate within the surgical instrument over a plurality of predefined zones; a motor comprising a shaft, the motor coupled to the displacement member to translate the displacement member; a control circuit coupled to the motor; a position sensor coupled to the control circuit, the position sensor configured to monitor the rotation of the shaft; a timer circuit coupled to the control circuit, the timer/counter circuit configured to measure elapsed time; wherein the control circuit is configured to: receive, from the position sensor, rotations of the shaft in a current zone defined by a set rotation interval; measure time at a set position of the rotation interval, wherein the measured time is defined as the time taken by the displacement member to traverse the rotation interval based on a predetermined number of shaft rotations; and set a command velocity of the displacement member for a subsequent zone based on the measured time in the current predefined zone.

In another aspect, the surgical instrument comprises a displacement member configured to translate within the surgical instrument over a plurality of predefined zones; a motor comprising a shaft, the motor coupled to the displacement member to translate the displacement member; a control circuit coupled to the motor; a position sensor coupled to the control circuit, the position sensor configured to monitor the rotation of the shaft; a timer circuit coupled to the control circuit, the timer/counter circuit configured to measure elapsed time; wherein the control circuit is configured to: receive, from the position sensor, rotations of the shaft in a current zone defined by a predetermined rotation interval; measure time as the displacement member moves from a parked position to a target position based on a predetermined number of shaft rotations; and set a command velocity of the displacement member for a first dynamic zone based on the measured time.

In another aspect, the present disclosure provides a method of controlling motor velocity in a surgical instrument, the surgical instrument comprising a displacement member configured to translate within the surgical instrument over a plurality of predefined zones, a motor comprising a shaft, the motor coupled to the displacement member to translate the displacement member, a control circuit coupled to the motor, a position sensor coupled to the control circuit, the position sensor configured to monitor the rotation of the shaft, a timer circuit coupled to the control circuit, the timer/counter circuit configured to measure elapsed time, the method comprising: receiving, from a position sensor, rotations of the shaft in a current zone defined by a set rotation interval; measuring, by a timer circuit, a time at a set position of the of the rotation interval, wherein the measured time is defined by the time taken by the displacement member to traverse the rotation interval based on a predetermined number of shaft rotations; and setting, by the control circuit, a command velocity of the displacement member for a subsequent zone based on the measured time in the current zone.

FIGURES

The novel features of the aspects described herein are set forth with particularity in the appended claims. These aspects, however, both as to organization and methods of operation may be better understood by reference to the following description, taken in conjunction with the accompanying drawings.

FIG. 1 is a perspective view of a surgical instrument that has an interchangeable shaft assembly operably coupled thereto according to one aspect of this disclosure.

FIG. 2 is an exploded assembly view of a portion of the surgical instrument of FIG. 1 according to one aspect of this disclosure.

FIG. 3 is an exploded assembly view of portions of the interchangeable shaft assembly according to one aspect of this disclosure.

FIG. 4 is an exploded view of an end effector of the surgical instrument of FIG. 1 according to one aspect of this disclosure.

FIGS. 5A-5B is a block diagram of a control circuit of the surgical instrument of FIG. 1 spanning two drawing sheets according to one aspect of this disclosure.

FIG. 6 is a block diagram of the control circuit of the surgical instrument of FIG. 1 illustrating interfaces between the handle assembly, the power assembly, and the handle assembly and the interchangeable shaft assembly according to one aspect of this disclosure.

FIG. 7 illustrates a control circuit configured to control aspects of the surgical instrument of FIG. 1 according to one aspect of this disclosure.

FIG. 8 illustrates a combinational logic circuit configured to control aspects of the surgical instrument of FIG. 1 according to one aspect of this disclosure.

FIG. 9 illustrates a sequential logic circuit configured to control aspects of the surgical instrument of FIG. 1 according to one aspect of this disclosure.

FIG. 10 is a diagram of an absolute positioning system of the surgical instrument of FIG. 1 where the absolute positioning system comprises a controlled motor drive circuit arrangement comprising a sensor arrangement according to one aspect of this disclosure.

FIG. 11 is an exploded perspective view of the sensor arrangement for an absolute positioning system showing a control circuit board assembly and the relative alignment of the elements of the sensor arrangement according to one aspect of this disclosure.

FIG. 12 is a diagram of a position sensor comprising a magnetic rotary absolute positioning system according to one aspect of this disclosure.

FIG. 13 is a section view of an end effector of the surgical instrument of FIG. 1 showing a firing member stroke relative to tissue grasped within the end effector according to one aspect of this disclosure.

FIG. 14 illustrates a block diagram of a surgical instrument programmed to control distal translation of a displacement member according to one aspect of this disclosure.

FIG. 15 illustrates a diagram plotting two example displacement member strokes executed according to one aspect of this disclosure.

FIG. 16A illustrates an end effector comprising a firing member coupled to an I-beam comprising a cutting edge according to one aspect of this disclosure.

FIG. 16B illustrates an end effector where the I-beam is located in a target position at the top of a ramp with the top pin engaged in the T-slot according to one aspect of this disclosure.

FIG. 17 illustrates a screw drive system 10470 that may be employed with the surgical instrument 10 (FIG. 1) according to one aspect of this disclosure.

FIG. 18 illustrates the I-beam firing stroke is illustrated by a chart aligned with the end effector according to one aspect of this disclosure.

FIG. 19 is a graphical depiction comparing I-beam stroke displacement as a function of time (top graph) and expected force-to-fire as a function of time (bottom graph) according to one aspect of this disclosure.

FIG. 20 is a graphical depiction comparing tissue thickness as a function of set rotation interval of I-beam stroke (top graph), force to fire as a function of set rotation interval of I-beam stroke (second graph from the top), dynamic time checks as a function of set rotation interval of I-beam stroke (third graph from the top), and set velocity of I-beam as a function of set rotation interval of I-beam stroke (bottom graph) according to one aspect of this disclosure.

FIG. 21 is a graphical depiction of force to fire as a function of time comparing slow, medium and fast I-beam displacement velocities according to one aspect of this disclosure.

FIG. 22 is a logic flow diagram of a process depicting a control program or logic configuration for controlling command velocity in an initial firing stage according to one aspect of this disclosure.

FIG. 23 is a logic flow diagram of a process depicting a control program or logic configuration for controlling command velocity in a dynamic firing stage according to one aspect of this disclosure.

DESCRIPTION

Applicant of the present application owns the following patent applications filed concurrently herewith and which are each herein incorporated by reference in their respective entireties:

Attorney Docket No. END8191USNP/170054, titled CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON ANGLE OF ARTICULATION, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

Attorney Docket No. END8192USNP/170055, titled SURGICAL INSTRUMENT WITH VARIABLE DURATION TRIGGER ARRANGEMENT, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

Attorney Docket No. END8193USNP/170056, titled SYSTEMS AND METHODS FOR CONTROLLING DISPLACEMENT MEMBER MOTION OF A SURGICAL STAPLING AND CUTTING INSTRUMENT, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

Attorney Docket No. END8194USNP/170057, titled SYSTEMS AND METHODS FOR CONTROLLING MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT ACCORDING TO ARTICULATION ANGLE OF END EFFECTOR, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

Attorney Docket No. END8195USNP/170058, titled SYSTEMS AND METHODS FOR CONTROLLING MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

Attorney Docket No. END8196USNP/170059, titled SURGICAL INSTRUMENT HAVING CONTROLLABLE ARTICULATION VELOCITY, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

Attorney Docket No. END8197USNP/170060, titled SYSTEMS AND METHODS FOR CONTROLLING VELOCITY OF A DISPLACEMENT MEMBER OF A SURGICAL STAPLING AND CUTTING INSTRUMENT, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

Attorney Docket No. END8198USNP/170061, titled SYSTEMS AND METHODS FOR CONTROLLING DISPLACEMENT MEMBER VELOCITY FOR A SURGICAL INSTRUMENT, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

Attorney Docket No. END8222USNP/170125, titled CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON ANGLE OF ARTICULATION, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

Attorney Docket No. END8199USNP/170062M, titled TECHNIQUES FOR ADAPTIVE CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

Attorney Docket No. END8275USNP/170185M, titled TECHNIQUES FOR CLOSED LOOP CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT, by inventors Raymond E. Parfett et al., filed Jun. 20, 2017.

Attorney Docket No. END8268USNP/170186, titled CLOSED LOOP FEEDBACK CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON MAGNITUDE OF VELOCITY ERROR MEASUREMENTS, by inventors Raymond E. Parfett et al., filed Jun. 20, 2017.

Attorney Docket No. END8276USNP/170187, titled CLOSED LOOP FEEDBACK CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON MEASURED TIME OVER A SPECIFIED DISPLACEMENT DISTANCE, by inventors Jason L. Harris et al., filed Jun. 20, 2017.

Attorney Docket No. END8266USNP/170188, titled CLOSED LOOP FEEDBACK CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON MEASURED DISPLACEMENT DISTANCE TRAVELED OVER A SPECIFIED TIME INTERVAL, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

Attorney Docket No. END8269USNP/170190, titled SYSTEMS AND METHODS FOR CONTROLLING DISPLAYING MOTOR VELOCITY FOR A SURGICAL INSTRUMENT, by inventors Jason L. Harris et al., filed Jun. 20, 2017.

Attorney Docket No. END8270USNP/170191, titled SYSTEMS AND METHODS FOR CONTROLLING MOTOR SPEED ACCORDING TO USER INPUT FOR A SURGICAL INSTRUMENT, by inventors Jason L. Harris et al., filed Jun. 20, 2017.

Attorney Docket No. END8271USNP/170192, titled CLOSED LOOP FEEDBACK CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON SYSTEM CONDITIONS, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

Applicant of the present application owns the following U.S. Design Patent Applications filed concurrently herewith and which are each herein incorporated by reference in their respective entireties:

Attorney Docket No. END8274USDP/170193D, titled GRAPHICAL USER INTERFACE FOR A DISPLAY OR PORTION THEREOF, by inventors Jason L. Harris et al., filed Jun. 20, 2017.

Attorney Docket No. END8273USDP/170194D, titled GRAPHICAL USER INTERFACE FOR A DISPLAY OR PORTION THEREOF, by inventors Jason L. Harris et al., filed Jun. 20, 2017.

Attorney Docket No. END8272USDP/170195D, titled GRAPHICAL USER INTERFACE FOR A DISPLAY OR PORTION THEREOF, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

Certain aspects are shown and described to provide an understanding of the structure, function, manufacture, and use of the disclosed devices and methods. Features shown or described in one example may be combined with features of other examples and modifications and variations are within the scope of this disclosure.

The terms “proximal” and “distal” are relative to a clinician manipulating the handle of the surgical instrument where “proximal” refers to the portion closer to the clinician and “distal” refers to the portion located further from the clinician. For expediency, spatial terms “vertical,” “horizontal,” “up,” and “down” used with respect to the drawings are not intended to be limiting and/or absolute, because surgical instruments can used in many orientations and positions.

Example devices and methods are provided for performing laparoscopic and minimally invasive surgical procedures. Such devices and methods, however, can be used in other surgical procedures and applications including open surgical procedures, for example. The surgical instruments can be inserted into a through a natural orifice or through an incision or puncture hole formed in tissue. The working portions or end effector portions of the instruments can be inserted directly into the body or through an access device that has a working channel through which the end effector and elongated shaft of the surgical instrument can be advanced.

FIGS. 1-4 depict a motor-driven surgical instrument 10 for cutting and fastening that may or may not be reused. In the illustrated examples, the surgical instrument 10 includes a housing 12 that comprises a handle assembly 14 that is configured to be grasped, manipulated, and actuated by the clinician. The housing 12 is configured for operable attachment to an interchangeable shaft assembly 200 that has an end effector 300 operably coupled thereto that is configured to perform one or more surgical tasks or procedures. In accordance with the present disclosure, various forms of interchangeable shaft assemblies may be effectively employed in connection with robotically controlled surgical systems. The term “housing” may encompass a housing or similar portion of a robotic system that houses or otherwise operably supports at least one drive system configured to generate and apply at least one control motion that could be used to actuate interchangeable shaft assemblies. The term “frame” may refer to a portion of a handheld surgical instrument. The term “frame” also may represent a portion of a robotically controlled surgical instrument and/or a portion of the robotic system that may be used to operably control a surgical instrument. Interchangeable shaft assemblies may be employed with various robotic systems, instruments, components, and methods disclosed in U.S. Pat. No. 9,072,535, entitled SURGICAL STAPLING INSTRUMENTS WITH ROTATABLE STAPLE DEPLOYMENT ARRANGEMENTS, which is herein incorporated by reference in its entirety.

FIG. 1 is a perspective view of a surgical instrument 10 that has an interchangeable shaft assembly 200 operably coupled thereto according to one aspect of this disclosure. The housing 12 includes an end effector 300 that comprises a surgical cutting and fastening device configured to operably support a surgical staple cartridge 304 therein. The housing 12 may be configured for use in connection with interchangeable shaft assemblies that include end effectors that are adapted to support different sizes and types of staple cartridges, have different shaft lengths, sizes, and types. The housing 12 may be employed with a variety of interchangeable shaft assemblies, including assemblies configured to apply other motions and forms of energy such as, radio frequency (RF) energy, ultrasonic energy, and/or motion to end effector arrangements adapted for use in connection with various surgical applications and procedures. The end effectors, shaft assemblies, handles, surgical instruments, and/or surgical instrument systems can utilize any suitable fastener, or fasteners, to fasten tissue. For instance, a fastener cartridge comprising a plurality of fasteners removably stored therein can be removably inserted into and/or attached to the end effector of a shaft assembly.

The handle assembly 14 may comprise a pair of interconnectable handle housing segments 16, 18 interconnected by screws, snap features, adhesive, etc. The handle housing segments 16, 18 cooperate to form a pistol grip portion 19 that can be gripped and manipulated by the clinician. The handle assembly 14 operably supports a plurality of drive systems configured to generate and apply control motions to corresponding portions of the interchangeable shaft assembly that is operably attached thereto. A display may be provided below a cover 45.

FIG. 2 is an exploded assembly view of a portion of the surgical instrument 10 of FIG. 1 according to one aspect of this disclosure. The handle assembly 14 may include a frame 20 that operably supports a plurality of drive systems. The frame 20 can operably support a “first” or closure drive system 30, which can apply closing and opening motions to the interchangeable shaft assembly 200. The closure drive system 30 may include an actuator such as a closure trigger 32 pivotally supported by the frame 20. The closure trigger 32 is pivotally coupled to the handle assembly 14 by a pivot pin 33 to enable the closure trigger 32 to be manipulated by a clinician. When the clinician grips the pistol grip portion 19 of the handle assembly 14, the closure trigger 32 can pivot from a starting or “unactuated” position to an “actuated” position and more particularly to a fully compressed or fully actuated position.

The handle assembly 14 and the frame 20 may operably support a firing drive system 80 configured to apply firing motions to corresponding portions of the interchangeable shaft assembly attached thereto. The firing drive system 80 may employ an electric motor 82 located in the pistol grip portion 19 of the handle assembly 14. The electric motor 82 may be a DC brushed motor having a maximum rotational speed of approximately 25,000 RPM, for example. In other arrangements, the motor may include a brushless motor, a cordless motor, a synchronous motor, a stepper motor, or any other suitable electric motor. The electric motor 82 may be powered by a power source 90 that may comprise a removable power pack 92. The removable power pack 92 may comprise a proximal housing portion 94 configured to attach to a distal housing portion 96. The proximal housing portion 94 and the distal housing portion 96 are configured to operably support a plurality of batteries 98 therein. Batteries 98 may each comprise, for example, a Lithium Ion (LI) or other suitable battery. The distal housing portion 96 is configured for removable operable attachment to a control circuit board 100, which is operably coupled to the electric motor 82. Several batteries 98 connected in series may power the surgical instrument 10. The power source 90 may be replaceable and/or rechargeable. A display 43, which is located below the cover 45, is electrically coupled to the control circuit board 100. The cover 45 may be removed to expose the display 43.

The electric motor 82 can include a rotatable shaft (not shown) that operably interfaces with a gear reducer assembly 84 mounted in meshing engagement with a with a set, or rack, of drive teeth 122 on a longitudinally movable drive member 120. The longitudinally movable drive member 120 has a rack of drive teeth 122 formed thereon for meshing engagement with a corresponding drive gear 86 of the gear reducer assembly 84.

In use, a voltage polarity provided by the power source 90 can operate the electric motor 82 in a clockwise direction wherein the voltage polarity applied to the electric motor by the battery can be reversed in order to operate the electric motor 82 in a counter-clockwise direction. When the electric motor 82 is rotated in one direction, the longitudinally movable drive member 120 will be axially driven in the distal direction “DD.” When the electric motor 82 is driven in the opposite rotary direction, the longitudinally movable drive member 120 will be axially driven in a proximal direction “PD.” The handle assembly 14 can include a switch that can be configured to reverse the polarity applied to the electric motor 82 by the power source 90. The handle assembly 14 may include a sensor configured to detect the position of the longitudinally movable drive member 120 and/or the direction in which the longitudinally movable drive member 120 is being moved.

Actuation of the electric motor 82 can be controlled by a firing trigger 130 that is pivotally supported on the handle assembly 14. The firing trigger 130 may be pivoted between an unactuated position and an actuated position.

Turning back to FIG. 1, the interchangeable shaft assembly 200 includes an end effector 300 comprising an elongated channel 302 configured to operably support a surgical staple cartridge 304 therein. The end effector 300 may include an anvil 306 that is pivotally supported relative to the elongated channel 302. The interchangeable shaft assembly 200 may include an articulation joint 270. Construction and operation of the end effector 300 and the articulation joint 270 are set forth in U.S. Patent Application Publication No. 2014/0263541, entitled ARTICULATABLE SURGICAL INSTRUMENT COMPRISING AN ARTICULATION LOCK, which is herein incorporated by reference in its entirety. The interchangeable shaft assembly 200 may include a proximal housing or nozzle 201 comprised of nozzle portions 202, 203. The interchangeable shaft assembly 200 may include a closure tube 260 extending along a shaft axis SA that can be utilized to close and/or open the anvil 306 of the end effector 300.

Turning back to FIG. 1, the closure tube 260 is translated distally (direction “DD”) to close the anvil 306, for example, in response to the actuation of the closure trigger 32 in the manner described in the aforementioned reference U.S. Patent Application Publication No. 2014/0263541. The anvil 306 is opened by proximally translating the closure tube 260. In the anvil-open position, the closure tube 260 is moved to its proximal position.

FIG. 3 is another exploded assembly view of portions of the interchangeable shaft assembly 200 according to one aspect of this disclosure. The interchangeable shaft assembly 200 may include a firing member 220 supported for axial travel within the spine 210. The firing member 220 includes an intermediate firing shaft 222 configured to attach to a distal cutting portion or knife bar 280. The firing member 220 may be referred to as a “second shaft” or a “second shaft assembly”. The intermediate firing shaft 222 may include a longitudinal slot 223 in a distal end configured to receive a tab 284 on the proximal end 282 of the knife bar 280. The longitudinal slot 223 and the proximal end 282 may be configured to permit relative movement there between and can comprise a slip joint 286. The slip joint 286 can permit the intermediate firing shaft 222 of the firing member 220 to articulate the end effector 300 about the articulation joint 270 without moving, or at least substantially moving, the knife bar 280. Once the end effector 300 has been suitably oriented, the intermediate firing shaft 222 can be advanced distally until a proximal sidewall of the longitudinal slot 223 contacts the tab 284 to advance the knife bar 280 and fire the staple cartridge positioned within the channel 302. The spine 210 has an elongated opening or window 213 therein to facilitate assembly and insertion of the intermediate firing shaft 222 into the spine 210. Once the intermediate firing shaft 222 has been inserted therein, a top frame segment 215 may be engaged with the shaft frame 212 to enclose the intermediate firing shaft 222 and knife bar 280 therein. Operation of the firing member 220 may be found in U.S. Patent Application Publication No. 2014/0263541. A spine 210 can be configured to slidably support a firing member 220 and the closure tube 260 that extends around the spine 210. The spine 210 may slidably support an articulation driver 230.

The interchangeable shaft assembly 200 can include a clutch assembly 400 configured to selectively and releasably couple the articulation driver 230 to the firing member 220. The clutch assembly 400 includes a lock collar, or lock sleeve 402, positioned around the firing member 220 wherein the lock sleeve 402 can be rotated between an engaged position in which the lock sleeve 402 couples the articulation driver 230 to the firing member 220 and a disengaged position in which the articulation driver 230 is not operably coupled to the firing member 220. When the lock sleeve 402 is in the engaged position, distal movement of the firing member 220 can move the articulation driver 230 distally and, correspondingly, proximal movement of the firing member 220 can move the articulation driver 230 proximally. When the lock sleeve 402 is in the disengaged position, movement of the firing member 220 is not transmitted to the articulation driver 230 and, as a result, the firing member 220 can move independently of the articulation driver 230. The nozzle 201 may be employed to operably engage and disengage the articulation drive system with the firing drive system in the various manners described in U.S. Patent Application Publication No. 2014/0263541.

The interchangeable shaft assembly 200 can comprise a slip ring assembly 600 which can be configured to conduct electrical power to and/or from the end effector 300 and/or communicate signals to and/or from the end effector 300, for example. The slip ring assembly 600 can comprise a proximal connector flange 604 and a distal connector flange 601 positioned within a slot defined in the nozzle portions 202, 203. The proximal connector flange 604 can comprise a first face and the distal connector flange 601 can comprise a second face positioned adjacent to and movable relative to the first face. The distal connector flange 601 can rotate relative to the proximal connector flange 604 about the shaft axis SA-SA (FIG. 1). The proximal connector flange 604 can comprise a plurality of concentric, or at least substantially concentric, conductors 602 defined in the first face thereof. A connector 607 can be mounted on the proximal side of the distal connector flange 601 and may have a plurality of contacts wherein each contact corresponds to and is in electrical contact with one of the conductors 602. Such an arrangement permits relative rotation between the proximal connector flange 604 and the distal connector flange 601 while maintaining electrical contact there between. The proximal connector flange 604 can include an electrical connector 606 that can place the conductors 602 in signal communication with a shaft circuit board, for example. In at least one instance, a wiring harness comprising a plurality of conductors can extend between the electrical connector 606 and the shaft circuit board. The electrical connector 606 may extend proximally through a connector opening defined in the chassis mounting flange. U.S. Patent Application Publication No. 2014/0263551, entitled STAPLE CARTRIDGE TISSUE THICKNESS SENSOR SYSTEM, is incorporated herein by reference in its entirety. U.S. Patent Application Publication No. 2014/0263552, entitled STAPLE CARTRIDGE TISSUE THICKNESS SENSOR SYSTEM, is incorporated by reference in its entirety. Further details regarding slip ring assembly 600 may be found in U.S. Patent Application Publication No. 2014/0263541.

The interchangeable shaft assembly 200 can include a proximal portion fixably mounted to the handle assembly 14 and a distal portion that is rotatable about a longitudinal axis. The rotatable distal shaft portion can be rotated relative to the proximal portion about the slip ring assembly 600. The distal connector flange 601 of the slip ring assembly 600 can be positioned within the rotatable distal shaft portion.

FIG. 4 is an exploded view of one aspect of an end effector 300 of the surgical instrument 10 of FIG. 1 according to one aspect of this disclosure. The end effector 300 may include the anvil 306 and the surgical staple cartridge 304. The anvil 306 may be coupled to an elongated channel 302. Apertures 199 can be defined in the elongated channel 302 to receive pins 152 extending from the anvil 306 to allow the anvil 306 to pivot from an open position to a closed position relative to the elongated channel 302 and surgical staple cartridge 304. A firing bar 172 is configured to longitudinally translate into the end effector 300. The firing bar 172 may be constructed from one solid section, or may include a laminate material comprising a stack of steel plates. The firing bar 172 comprises an I-beam 178 and a cutting edge 182 at a distal end thereof. A distally projecting end of the firing bar 172 can be attached to the I-beam 178 to assist in spacing the anvil 306 from a surgical staple cartridge 304 positioned in the elongated channel 302 when the anvil 306 is in a closed position. The I-beam 178 may include a sharpened cutting edge 182 to sever tissue as the I-beam 178 is advanced distally by the firing bar 172. In operation, the I-beam 178 may, or fire, the surgical staple cartridge 304. The surgical staple cartridge 304 can include a molded cartridge body 194 that holds a plurality of staples 191 resting upon staple drivers 192 within respective upwardly open staple cavities 195. A wedge sled 190 is driven distally by the I-beam 178, sliding upon a cartridge tray 196 of the surgical staple cartridge 304. The wedge sled 190 upwardly cams the staple drivers 192 to force out the staples 191 into deforming contact with the anvil 306 while the cutting edge 182 of the I-beam 178 severs clamped tissue.

The I-beam 178 can include upper pins 180 that engage the anvil 306 during firing. The I-beam 178 may include middle pins 184 and a bottom foot 186 to engage portions of the cartridge body 194, cartridge tray 196, and elongated channel 302. When a surgical staple cartridge 304 is positioned within the elongated channel 302, a slot 193 defined in the cartridge body 194 can be aligned with a longitudinal slot 197 defined in the cartridge tray 196 and a slot 189 defined in the elongated channel 302. In use, the I-beam 178 can slide through the aligned longitudinal slots 193, 197, and 189 wherein, as indicated in FIG. 4, the bottom foot 186 of the I-beam 178 can engage a groove running along the bottom surface of elongated channel 302 along the length of slot 189, the middle pins 184 can engage the top surfaces of cartridge tray 196 along the length of longitudinal slot 197, and the upper pins 180 can engage the anvil 306. The I-beam 178 can space, or limit the relative movement between, the anvil 306 and the surgical staple cartridge 304 as the firing bar 172 is advanced distally to fire the staples from the surgical staple cartridge 304 and/or incise the tissue captured between the anvil 306 and the surgical staple cartridge 304. The firing bar 172 and the I-beam 178 can be retracted proximally allowing the anvil 306 to be opened to release the two stapled and severed tissue portions.

FIGS. 5A-5B is a block diagram of a control circuit 700 of the surgical instrument 10 of FIG. 1 spanning two drawing sheets according to one aspect of this disclosure. Referring primarily to FIGS. 5A-5B, a handle assembly 702 may include a motor 714 which can be controlled by a motor driver 715 and can be employed by the firing system of the surgical instrument 10. In various forms, the motor 714 may be a DC brushed driving motor having a maximum rotational speed of approximately 25,000 RPM. In other arrangements, the motor 714 may include a brushless motor, a cordless motor, a synchronous motor, a stepper motor, or any other suitable electric motor. The motor driver 715 may comprise an H-Bridge driver comprising field-effect transistors (FETs) 719, for example. The motor 714 can be powered by the power assembly 706 releasably mounted to the handle assembly 200 for supplying control power to the surgical instrument 10. The power assembly 706 may comprise a battery which may include a number of battery cells connected in series that can be used as the power source to power the surgical instrument 10. In certain circumstances, the battery cells of the power assembly 706 may be replaceable and/or rechargeable. In at least one example, the battery cells can be Lithium-Ion batteries which can be separably couplable to the power assembly 706.

The shaft assembly 704 may include a shaft assembly controller 722 which can communicate with a safety controller and power management controller 716 through an interface while the shaft assembly 704 and the power assembly 706 are coupled to the handle assembly 702. For example, the interface may comprise a first interface portion 725 which may include one or more electric connectors for coupling engagement with corresponding shaft assembly electric connectors and a second interface portion 727 which may include one or more electric connectors for coupling engagement with corresponding power assembly electric connectors to permit electrical communication between the shaft assembly controller 722 and the power management controller 716 while the shaft assembly 704 and the power assembly 706 are coupled to the handle assembly 702. One or more communication signals can be transmitted through the interface to communicate one or more of the power requirements of the attached interchangeable shaft assembly 704 to the power management controller 716. In response, the power management controller may modulate the power output of the battery of the power assembly 706, as described below in greater detail, in accordance with the power requirements of the attached shaft assembly 704. The connectors may comprise switches which can be activated after mechanical coupling engagement of the handle assembly 702 to the shaft assembly 704 and/or to the power assembly 706 to allow electrical communication between the shaft assembly controller 722 and the power management controller 716.

The interface can facilitate transmission of the one or more communication signals between the power management controller 716 and the shaft assembly controller 722 by routing such communication signals through a main controller 717 residing in the handle assembly 702, for example. In other circumstances, the interface can facilitate a direct line of communication between the power management controller 716 and the shaft assembly controller 722 through the handle assembly 702 while the shaft assembly 704 and the power assembly 706 are coupled to the handle assembly 702.

The main controller 717 may be any single core or multicore processor such as those known under the trade name ARM Cortex by Texas Instruments. In one aspect, the main controller 717 may be an LM4F230H5QR ARM Cortex-M4F Processor Core, available from Texas Instruments, for example, comprising on-chip memory of 256 KB single-cycle flash memory, or other non-volatile memory, up to 40 MHz, a prefetch buffer to improve performance above 40 MHz, a 32 KB single-cycle serial random access memory (SRAM), internal read-only memory (ROM) loaded with StellarisWare® software, 2 KB electrically erasable programmable read-only memory (EEPROM), one or more pulse width modulation (PWM) modules, one or more quadrature encoder inputs (QEI) analog, one or more 12-bit Analog-to-Digital Converters (ADC) with 12 analog input channels, details of which are available for the product datasheet.

The safety controller may be a safety controller platform comprising two controller-based families such as TMS570 and RM4x known under the trade name Hercules ARM Cortex R4, also by Texas Instruments. The safety controller may be configured specifically for IEC 61508 and ISO 26262 safety critical applications, among others, to provide advanced integrated safety features while delivering scalable performance, connectivity, and memory options.

The power assembly 706 may include a power management circuit which may comprise the power management controller 716, a power modulator 738, and a current sense circuit 736. The power management circuit can be configured to modulate power output of the battery based on the power requirements of the shaft assembly 704 while the shaft assembly 704 and the power assembly 706 are coupled to the handle assembly 702. The power management controller 716 can be programmed to control the power modulator 738 of the power output of the power assembly 706 and the current sense circuit 736 can be employed to monitor power output of the power assembly 706 to provide feedback to the power management controller 716 about the power output of the battery so that the power management controller 716 may adjust the power output of the power assembly 706 to maintain a desired output. The power management controller 716 and/or the shaft assembly controller 722 each may comprise one or more processors and/or memory units which may store a number of software modules.

The surgical instrument 10 (FIGS. 1-4) may comprise an output device 742 which may include devices for providing a sensory feedback to a user. Such devices may comprise, for example, visual feedback devices (e.g., an LCD display screen, LED indicators), audio feedback devices (e.g., a speaker, a buzzer) or tactile feedback devices (e.g., haptic actuators). In certain circumstances, the output device 742 may comprise a display 743 which may be included in the handle assembly 702. The shaft assembly controller 722 and/or the power management controller 716 can provide feedback to a user of the surgical instrument 10 through the output device 742. The interface can be configured to connect the shaft assembly controller 722 and/or the power management controller 716 to the output device 742. The output device 742 can instead be integrated with the power assembly 706. In such circumstances, communication between the output device 742 and the shaft assembly controller 722 may be accomplished through the interface while the shaft assembly 704 is coupled to the handle assembly 702.

The control circuit 700 comprises circuit segments configured to control operations of the powered surgical instrument 10. A safety controller segment (Segment 1) comprises a safety controller and the main controller 717 segment (Segment 2). The safety controller and/or the main controller 717 are configured to interact with one or more additional circuit segments such as an acceleration segment, a display segment, a shaft segment, an encoder segment, a motor segment, and a power segment. Each of the circuit segments may be coupled to the safety controller and/or the main controller 717. The main controller 717 is also coupled to a flash memory. The main controller 717 also comprises a serial communication interface. The main controller 717 comprises a plurality of inputs coupled to, for example, one or more circuit segments, a battery, and/or a plurality of switches. The segmented circuit may be implemented by any suitable circuit, such as, for example, a printed circuit board assembly (PCBA) within the powered surgical instrument 10. It should be understood that the term processor as used herein includes any microprocessor, processors, controller, controllers, or other basic computing device that incorporates the functions of a computer's central processing unit (CPU) on an integrated circuit or at most a few integrated circuits. The main controller 717 is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and provides results as output. It is an example of sequential digital logic, as it has internal memory. The control circuit 700 can be configured to implement one or more of the processes described herein.

The acceleration segment (Segment 3) comprises an accelerometer. The accelerometer is configured to detect movement or acceleration of the powered surgical instrument 10. Input from the accelerometer may be used to transition to and from a sleep mode, identify an orientation of the powered surgical instrument, and/or identify when the surgical instrument has been dropped. In some examples, the acceleration segment is coupled to the safety controller and/or the main controller 717.

The display segment (Segment 4) comprises a display connector coupled to the main controller 717. The display connector couples the main controller 717 to a display through one or more integrated circuit drivers of the display. The integrated circuit drivers of the display may be integrated with the display and/or may be located separately from the display. The display may comprise any suitable display, such as, for example, an organic light-emitting diode (OLED) display, a liquid-crystal display (LCD), and/or any other suitable display. In some examples, the display segment is coupled to the safety controller.

The shaft segment (Segment 5) comprises controls for an interchangeable shaft assembly 200 (FIGS. 1 and 3) coupled to the surgical instrument 10 (FIGS. 1-4) and/or one or more controls for an end effector 300 coupled to the interchangeable shaft assembly 200. The shaft segment comprises a shaft connector configured to couple the main controller 717 to a shaft PCBA. The shaft PCBA comprises a low-power microcontroller with a ferroelectric random access memory (FRAM), an articulation switch, a shaft release Hall effect switch, and a shaft PCBA EEPROM. The shaft PCBA EEPROM comprises one or more parameters, routines, and/or programs specific to the interchangeable shaft assembly 200 and/or the shaft PCBA. The shaft PCBA may be coupled to the interchangeable shaft assembly 200 and/or integral with the surgical instrument 10. In some examples, the shaft segment comprises a second shaft EEPROM. The second shaft EEPROM comprises a plurality of algorithms, routines, parameters, and/or other data corresponding to one or more shaft assemblies 200 and/or end effectors 300 that may be interfaced with the powered surgical instrument 10.

The position encoder segment (Segment 6) comprises one or more magnetic angle rotary position encoders. The one or more magnetic angle rotary position encoders are configured to identify the rotational position of the motor 714, an interchangeable shaft assembly 200 (FIGS. 1 and 3), and/or an end effector 300 of the surgical instrument 10 (FIGS. 1-4). In some examples, the magnetic angle rotary position encoders may be coupled to the safety controller and/or the main controller 717.

The motor circuit segment (Segment 7) comprises a motor 714 configured to control movements of the powered surgical instrument 10 (FIGS. 1-4). The motor 714 is coupled to the main microcontroller processor 717 by an H-bridge driver comprising one or more H-bridge field-effect transistors (FETs) and a motor controller. The H-bridge driver is also coupled to the safety controller. A motor current sensor is coupled in series with the motor to measure the current draw of the motor. The motor current sensor is in signal communication with the main controller 717 and/or the safety controller. In some examples, the motor 714 is coupled to a motor electromagnetic interference (EMI) filter.

The motor controller controls a first motor flag and a second motor flag to indicate the status and position of the motor 714 to the main controller 717. The main controller 717 provides a pulse-width modulation (PWM) high signal, a PWM low signal, a direction signal, a synchronize signal, and a motor reset signal to the motor controller through a buffer. The power segment is configured to provide a segment voltage to each of the circuit segments.

The power segment (Segment 8) comprises a battery coupled to the safety controller, the main controller 717, and additional circuit segments. The battery is coupled to the segmented circuit by a battery connector and a current sensor. The current sensor is configured to measure the total current draw of the segmented circuit. In some examples, one or more voltage converters are configured to provide predetermined voltage values to one or more circuit segments. For example, in some examples, the segmented circuit may comprise 3.3V voltage converters and/or 5V voltage converters. A boost converter is configured to provide a boost voltage up to a predetermined amount, such as, for example, up to 13V. The boost converter is configured to provide additional voltage and/or current during power intensive operations and prevent brownout or low-power conditions.

A plurality of switches are coupled to the safety controller and/or the main controller 717. The switches may be configured to control operations of the surgical instrument 10 (FIGS. 1-4), of the segmented circuit, and/or indicate a status of the surgical instrument 10. A bail-out door switch and Hall effect switch for bailout are configured to indicate the status of a bail-out door. A plurality of articulation switches, such as, for example, a left side articulation left switch, a left side articulation right switch, a left side articulation center switch, a right side articulation left switch, a right side articulation right switch, and a right side articulation center switch are configured to control articulation of an interchangeable shaft assembly 200 (FIGS. 1 and 3) and/or the end effector 300 (FIGS. 1 and 4). A left side reverse switch and a right side reverse switch are coupled to the main controller 717. The left side switches comprising the left side articulation left switch, the left side articulation right switch, the left side articulation center switch, and the left side reverse switch are coupled to the main controller 717 by a left flex connector. The right side switches comprising the right side articulation left switch, the right side articulation right switch, the right side articulation center switch, and the right side reverse switch are coupled to the main controller 717 by a right flex connector. A firing switch, a clamp release switch, and a shaft engaged switch are coupled to the main controller 717.

Any suitable mechanical, electromechanical, or solid state switches may be employed to implement the plurality of switches, in any combination. For example, the switches may be limit switches operated by the motion of components associated with the surgical instrument 10 (FIGS. 1-4) or the presence of an object. Such switches may be employed to control various functions associated with the surgical instrument 10. A limit switch is an electromechanical device that consists of an actuator mechanically linked to a set of contacts. When an object comes into contact with the actuator, the device operates the contacts to make or break an electrical connection. Limit switches are used in a variety of applications and environments because of their ruggedness, ease of installation, and reliability of operation. They can determine the presence or absence, passing, positioning, and end of travel of an object. In other implementations, the switches may be solid state switches that operate under the influence of a magnetic field such as Hall-effect devices, magneto-resistive (MR) devices, giant magneto-resistive (GMR) devices, magnetometers, among others. In other implementations, the switches may be solid state switches that operate under the influence of light, such as optical sensors, infrared sensors, ultraviolet sensors, among others. Still, the switches may be solid state devices such as transistors (e.g., FET, Junction-FET, metal-oxide semiconductor-FET (MOSFET), bipolar, and the like). Other switches may include wireless switches, ultrasonic switches, accelerometers, inertial sensors, among others.

FIG. 6 is another block diagram of the control circuit 700 of the surgical instrument of FIG. 1 illustrating interfaces between the handle assembly 702 and the power assembly 706 and between the handle assembly 702 and the interchangeable shaft assembly 704 according to one aspect of this disclosure. The handle assembly 702 may comprise a main controller 717, a shaft assembly connector 726 and a power assembly connector 730. The power assembly 706 may include a power assembly connector 732, a power management circuit 734 that may comprise the power management controller 716, a power modulator 738, and a current sense circuit 736. The shaft assembly connectors 730, 732 form an interface 727. The power management circuit 734 can be configured to modulate power output of the battery 707 based on the power requirements of the interchangeable shaft assembly 704 while the interchangeable shaft assembly 704 and the power assembly 706 are coupled to the handle assembly 702. The power management controller 716 can be programmed to control the power modulator 738 of the power output of the power assembly 706 and the current sense circuit 736 can be employed to monitor power output of the power assembly 706 to provide feedback to the power management controller 716 about the power output of the battery 707 so that the power management controller 716 may adjust the power output of the power assembly 706 to maintain a desired output. The shaft assembly 704 comprises a shaft processor 719 coupled to a non-volatile memory 721 and shaft assembly connector 728 to electrically couple the shaft assembly 704 to the handle assembly 702. The shaft assembly connectors 726, 728 form interface 725. The main controller 717, the shaft processor 719, and/or the power management controller 716 can be configured to implement one or more of the processes described herein.

The surgical instrument 10 (FIGS. 1-4) may comprise an output device 742 to a sensory feedback to a user. Such devices may comprise visual feedback devices (e.g., an LCD display screen, LED indicators), audio feedback devices (e.g., a speaker, a buzzer), or tactile feedback devices (e.g., haptic actuators). In certain circumstances, the output device 742 may comprise a display 743 that may be included in the handle assembly 702. The shaft assembly controller 722 and/or the power management controller 716 can provide feedback to a user of the surgical instrument 10 through the output device 742. The interface 727 can be configured to connect the shaft assembly controller 722 and/or the power management controller 716 to the output device 742. The output device 742 can be integrated with the power assembly 706. Communication between the output device 742 and the shaft assembly controller 722 may be accomplished through the interface 725 while the interchangeable shaft assembly 704 is coupled to the handle assembly 702. Having described a control circuit 700 (FIGS. 5A-5B and 6) for controlling the operation of the surgical instrument 10 (FIGS. 1-4), the disclosure now turns to various configurations of the surgical instrument 10 (FIGS. 1-4) and control circuit 700.

FIG. 7 illustrates a control circuit 800 configured to control aspects of the surgical instrument 10 (FIGS. 1-4) according to one aspect of this disclosure. The control circuit 800 can be configured to implement various processes described herein. The control circuit 800 may comprise a controller comprising one or more processors 802 (e.g., microprocessor, microcontroller) coupled to at least one memory circuit 804. The memory circuit 804 stores machine executable instructions that when executed by the processor 802, cause the processor 802 to execute machine instructions to implement various processes described herein. The processor 802 may be any one of a number of single or multi-core processors known in the art. The memory circuit 804 may comprise volatile and non-volatile storage media. The processor 802 may include an instruction processing unit 806 and an arithmetic unit 808. The instruction processing unit may be configured to receive instructions from the memory circuit 804.

FIG. 8 illustrates a combinational logic circuit 810 configured to control aspects of the surgical instrument 10 (FIGS. 1-4) according to one aspect of this disclosure. The combinational logic circuit 810 can be configured to implement various processes described herein. The circuit 810 may comprise a finite state machine comprising a combinational logic circuit 812 configured to receive data associated with the surgical instrument 10 at an input 814, process the data by the combinational logic 812, and provide an output 816.

FIG. 9 illustrates a sequential logic circuit 820 configured to control aspects of the surgical instrument 10 (FIGS. 1-4) according to one aspect of this disclosure. The sequential logic circuit 820 or the combinational logic circuit 822 can be configured to implement various processes described herein. The circuit 820 may comprise a finite state machine. The sequential logic circuit 820 may comprise a combinational logic circuit 822, at least one memory circuit 824, and a clock 829, for example. The at least one memory circuit 820 can store a current state of the finite state machine. In certain instances, the sequential logic circuit 820 may be synchronous or asynchronous. The combinational logic circuit 822 is configured to receive data associated with the surgical instrument 10 an input 826, process the data by the combinational logic circuit 822, and provide an output 828. In other aspects, the circuit may comprise a combination of the processor 802 and the finite state machine to implement various processes herein. In other aspects, the finite state machine may comprise a combination of the combinational logic circuit 810 and the sequential logic circuit 820.

Aspects may be implemented as an article of manufacture. The article of manufacture may include a computer readable storage medium arranged to store logic, instructions, and/or data for performing various operations of one or more aspects. For example, the article of manufacture may comprise a magnetic disk, optical disk, flash memory, or firmware containing computer program instructions suitable for execution by a general purpose processor or application specific processor.

FIG. 10 is a diagram of an absolute positioning system 1100 of the surgical instrument 10 (FIGS. 1-4) where the absolute positioning system 1100 comprises a controlled motor drive circuit arrangement comprising a sensor arrangement 1102 according to one aspect of this disclosure. The sensor arrangement 1102 for an absolute positioning system 1100 provides a unique position signal corresponding to the location of a displacement member 1111. Turning briefly to FIGS. 2-4, in one aspect the displacement member 1111 represents the longitudinally movable drive member 120 (FIG. 2) comprising a rack of drive teeth 122 for meshing engagement with a corresponding drive gear 86 of the gear reducer assembly 84. In other aspects, the displacement member 1111 represents the firing member 220 (FIG. 3), which could be adapted and configured to include a rack of drive teeth. In yet another aspect, the displacement member 1111 represents the firing bar 172 (FIG. 4) or the I-beam 178 (FIG. 4), each of which can be adapted and configured to include a rack of drive teeth. Accordingly, as used herein, the term displacement member is used generically to refer to any movable member of the surgical instrument 10 such as the drive member 120, the firing member 220, the firing bar 172, the I-beam 178, or any element that can be displaced. In one aspect, the longitudinally movable drive member 120 is coupled to the firing member 220, the firing bar 172, and the I-beam 178. Accordingly, the absolute positioning system 1100 can, in effect, track the linear displacement of the I-beam 178 by tracking the linear displacement of the longitudinally movable drive member 120. In various other aspects, the displacement member 1111 may be coupled to any sensor suitable for measuring linear displacement. Thus, the longitudinally movable drive member 120, the firing member 220, the firing bar 172, or the I-beam 178, or combinations, may be coupled to any suitable linear displacement sensor. Linear displacement sensors may include contact or non-contact displacement sensors. Linear displacement sensors may comprise linear variable differential transformers (LVDT), differential variable reluctance transducers (DVRT), a slide potentiometer, a magnetic sensing system comprising a movable magnet and a series of linearly arranged Hall effect sensors, a magnetic sensing system comprising a fixed magnet and a series of movable linearly arranged Hall effect sensors, an optical sensing system comprising a movable light source and a series of linearly arranged photo diodes or photo detectors, or an optical sensing system comprising a fixed light source and a series of movable linearly arranged photo diodes or photo detectors, or any combination thereof.

An electric motor 1120 can include a rotatable shaft 1116 that operably interfaces with a gear assembly 1114 that is mounted in meshing engagement with a set, or rack, of drive teeth on the displacement member 1111. A sensor element 1126 may be operably coupled to a gear assembly 1114 such that a single revolution of the sensor element 1126 corresponds to some linear longitudinal translation of the displacement member 1111. An arrangement of gearing and sensors 1118 can be connected to the linear actuator via a rack and pinion arrangement or a rotary actuator via a spur gear or other connection. A power source 1129 supplies power to the absolute positioning system 1100 and an output indicator 1128 may display the output of the absolute positioning system 1100. In FIG. 2, the displacement member 1111 represents the longitudinally movable drive member 120 comprising a rack of drive teeth 122 formed thereon for meshing engagement with a corresponding drive gear 86 of the gear reducer assembly 84. The displacement member 1111 represents the longitudinally movable firing member 220, firing bar 172, I-beam 178, or combinations thereof.

A single revolution of the sensor element 1126 associated with the position sensor 1112 is equivalent to a longitudinal linear displacement dl of the of the displacement member 1111, where dl is the longitudinal linear distance that the displacement member 1111 moves from point “a” to point “b” after a single revolution of the sensor element 1126 coupled to the displacement member 1111. The sensor arrangement 1102 may be connected via a gear reduction that results in the position sensor 1112 completing one or more revolutions for the full stroke of the displacement member 1111. The position sensor 1112 may complete multiple revolutions for the full stroke of the displacement member 1111.

A series of switches 1122 a-1122 n, where n is an integer greater than one, may be employed alone or in combination with gear reduction to provide a unique position signal for more than one revolution of the position sensor 1112. The state of the switches 1122 a-1122 n are fed back to a controller 1104 that applies logic to determine a unique position signal corresponding to the longitudinal linear displacement d1+d2+. . . dn of the displacement member 1111. The output 1124 of the position sensor 1112 is provided to the controller 1104. The position sensor 1112 of the sensor arrangement 1102 may comprise a magnetic sensor, an analog rotary sensor like a potentiometer, an array of analog Hall-effect elements, which output a unique combination of position signals or values.

The absolute positioning system 1100 provides an absolute position of the displacement member 1111 upon power up of the instrument without retracting or advancing the displacement member 1111 to a reset (zero or home) position as may be required with conventional rotary encoders that merely count the number of steps forwards or backwards that the motor 1120 has taken to infer the position of a device actuator, drive bar, knife, and the like.

The controller 1104 may be programmed to perform various functions such as precise control over the speed and position of the knife and articulation systems. In one aspect, the controller 1104 includes a processor 1108 and a memory 1106. The electric motor 1120 may be a brushed DC motor with a gearbox and mechanical links to an articulation or knife system. In one aspect, a motor driver 1110 may be an A3941 available from Allegro Microsystems, Inc. Other motor drivers may be readily substituted for use in the absolute positioning system 1100. A more detailed description of the absolute positioning system 1100 is described in U.S. patent application Ser. No. 15/130,590, entitled SYSTEMS AND METHODS FOR CONTROLLING A SURGICAL STAPLING AND CUTTING INSTRUMENT, filed on Apr. 15, 2016, the entire disclosure of which is herein incorporated by reference.

The controller 1104 may be programmed to provide precise control over the speed and position of the displacement member 1111 and articulation systems. The controller 1104 may be configured to compute a response in the software of the controller 1104. The computed response is compared to a measured response of the actual system to obtain an “observed” response, which is used for actual feedback decisions. The observed response is a favorable, tuned, value that balances the smooth, continuous nature of the simulated response with the measured response, which can detect outside influences on the system.

The absolute positioning system 1100 may comprise and/or be programmed to implement a feedback controller, such as a PID, state feedback, and adaptive controller. A power source 1129 converts the signal from the feedback controller into a physical input to the system, in this case voltage. Other examples include pulse width modulation (PWM) of the voltage, current, and force. Other sensor(s) 1118 may be provided to measure physical parameters of the physical system in addition to position measured by the position sensor 1112. In a digital signal processing system, absolute positioning system 1100 is coupled to a digital data acquisition system where the output of the absolute positioning system 1100 will have finite resolution and sampling frequency. The absolute positioning system 1100 may comprise a compare and combine circuit to combine a computed response with a measured response using algorithms such as weighted average and theoretical control loop that drives the computed response towards the measured response. The computed response of the physical system takes into account properties like mass, inertial, viscous friction, inductance resistance, etc., to predict what the states and outputs of the physical system will be by knowing the input. The controller 1104 may be a control circuit 700 (FIGS. 5A-5B).

The motor driver 1110 may be an A3941 available from Allegro Microsystems, Inc. The A3941 driver 1110 is a full-bridge controller for use with external N-channel power metal oxide semiconductor field effect transistors (MOSFETs) specifically designed for inductive loads, such as brush DC motors. The driver 1110 comprises a unique charge pump regulator provides full (>10 V) gate drive for battery voltages down to 7 V and allows the A3941 to operate with a reduced gate drive, down to 5.5 V. A bootstrap capacitor may be employed to provide the above-battery supply voltage required for N-channel MOSFETs. An internal charge pump for the high-side drive allows DC (100% duty cycle) operation. The full bridge can be driven in fast or slow decay modes using diode or synchronous rectification. In the slow decay mode, current recirculation can be through the high-side or the lowside FETs. The power FETs are protected from shoot-through by resistor adjustable dead time. Integrated diagnostics provide indication of undervoltage, overtemperature, and power bridge faults, and can be configured to protect the power MOSFETs under most short circuit conditions. Other motor drivers may be readily substituted for use in the absolute positioning system 1100.

Having described a general architecture for implementing aspects of an absolute positioning system 1100 for a sensor arrangement 1102, the disclosure now turns to FIGS. 11 and 12 for a description of one aspect of a sensor arrangement 1102 for the absolute positioning system 1100. FIG. 11 is an exploded perspective view of the sensor arrangement 1102 for the absolute positioning system 1100 showing a circuit 1205 and the relative alignment of the elements of the sensor arrangement 1102, according to one aspect. The sensor arrangement 1102 for an absolute positioning system 1100 comprises a position sensor 1200, a magnet 1202 sensor element, a magnet holder 1204 that turns once every full stroke of the displacement member 1111, and a gear assembly 1206 to provide a gear reduction. With reference briefly to FIG. 2, the displacement member 1111 may represent the longitudinally movable drive member 120 comprising a rack of drive teeth 122 for meshing engagement with a corresponding drive gear 86 of the gear reducer assembly 84. Returning to FIG. 11, a structural element such as bracket 1216 is provided to support the gear assembly 1206, the magnet holder 1204, and the magnet 1202. The position sensor 1200 comprises magnetic sensing elements such as Hall elements and is placed in proximity to the magnet 1202. As the magnet 1202 rotates, the magnetic sensing elements of the position sensor 1200 determine the absolute angular position of the magnet 1202 over one revolution.

The sensor arrangement 1102 may comprises any number of magnetic sensing elements, such as, for example, magnetic sensors classified according to whether they measure the total magnetic field or the vector components of the magnetic field. The techniques used to produce both types of magnetic sensors encompass many aspects of physics and electronics. The technologies used for magnetic field sensing include search coil, fluxgate, optically pumped, nuclear precession, SQUID, Hall-effect, anisotropic magnetoresistance, giant magnetoresistance, magnetic tunnel junctions, giant magnetoimpedance, magnetostrictive/piezoelectric composites, magnetodiode, magnetotransistor, fiber optic, magnetooptic, and microelectromechanical systems-based magnetic sensors, among others.

A gear assembly comprises a first gear 1208 and a second gear 1210 in meshing engagement to provide a 3:1 gear ratio connection. A third gear 1212 rotates about a shaft 1214. The third gear 1212 is in meshing engagement with the displacement member 1111 (or 120 as shown in FIG. 2) and rotates in a first direction as the displacement member 1111 advances in a distal direction D and rotates in a second direction as the displacement member 1111 retracts in a proximal direction P. The second gear 1210 also rotates about the shaft 1214 and, therefore, rotation of the second gear 1210 about the shaft 1214 corresponds to the longitudinal translation of the displacement member 1111. Thus, one full stroke of the displacement member 1111 in either the distal or proximal directions D, P corresponds to three rotations of the second gear 1210 and a single rotation of the first gear 1208. Since the magnet holder 1204 is coupled to the first gear 1208, the magnet holder 1204 makes one full rotation with each full stroke of the displacement member 1111.

The position sensor 1200 is supported by a position sensor holder 1218 defining an aperture 1220 suitable to contain the position sensor 1200 in precise alignment with a magnet 1202 rotating below within the magnet holder 1204. The fixture is coupled to the bracket 1216 and to the circuit 1205 and remains stationary while the magnet 1202 rotates with the magnet holder 1204. A hub 1222 is provided to mate with the first gear 1208 and the magnet holder 1204. The second gear 1210 and third gear 1212 coupled to shaft 1214 also are shown.

FIG. 12 is a diagram of a position sensor 1200 for an absolute positioning system 1100 comprising a magnetic rotary absolute positioning system according to one aspect of this disclosure. The position sensor 1200 may be implemented as an AS5055EQFT single-chip magnetic rotary position sensor available from Austria Microsystems, AG. The position sensor 1200 is interfaced with the controller 1104 to provide an absolute positioning system 1100. The position sensor 1200 is a low-voltage and low-power component and includes four Hall-effect elements 1228A, 1228B, 1228C, 1228D in an area 1230 of the position sensor 1200 that is located above the magnet 1202 (FIGS. 15 and 16). A high-resolution ADC 1232 and a smart power management controller 1238 are also provided on the chip. A CORDIC processor 1236 (for Coordinate Rotation Digital Computer), also known as the digit-by-digit method and Volder's algorithm, is provided to implement a simple and efficient algorithm to calculate hyperbolic and trigonometric functions that require only addition, subtraction, bitshift, and table lookup operations. The angle position, alarm bits, and magnetic field information are transmitted over a standard serial communication interface such as an SPI interface 1234 to the controller 1104. The position sensor 1200 provides 12 or 14 bits of resolution. The position sensor 1200 may be an AS5055 chip provided in a small QFN 16-pin 4×4×0.85 mm package.

The Hall-effect elements 1228A, 1228B, 1228C, 1228D are located directly above the rotating magnet 1202 (FIG. 11). The Hall-effect is a well-known effect and for expediency will not be described in detail herein, however, generally, the Hall-effect produces a voltage difference (the Hall voltage) across an electrical conductor transverse to an electric current in the conductor and a magnetic field perpendicular to the current. A Hall coefficient is defined as the ratio of the induced electric field to the product of the current density and the applied magnetic field. It is a characteristic of the material from which the conductor is made, since its value depends on the type, number, and properties of the charge carriers that constitute the current. In the AS5055 position sensor 1200, the Hall-effect elements 1228A, 1228B, 1228C, 1228D are capable producing a voltage signal that is indicative of the absolute position of the magnet 1202 in terms of the angle over a single revolution of the magnet 1202. This value of the angle, which is unique position signal, is calculated by the CORDIC processor 1236 is stored onboard the AS5055 position sensor 1200 in a register or memory. The value of the angle that is indicative of the position of the magnet 1202 over one revolution is provided to the controller 1104 in a variety of techniques, e.g., upon power up or upon request by the controller 1104.

The AS5055 position sensor 1200 requires only a few external components to operate when connected to the controller 1104. Six wires are needed for a simple application using a single power supply: two wires for power and four wires 1240 for the SPI interface 1234 with the controller 1104. A seventh connection can be added in order to send an interrupt to the controller 1104 to inform that a new valid angle can be read. Upon power-up, the AS5055 position sensor 1200 performs a full power-up sequence including one angle measurement. The completion of this cycle is indicated as an INT output 1242, and the angle value is stored in an internal register. Once this output is set, the AS5055 position sensor 1200 suspends to sleep mode. The controller 1104 can respond to the INT request at the INT output 1242 by reading the angle value from the AS5055 position sensor 1200 over the SPI interface 1234. Once the angle value is read by the controller 1104, the INT output 1242 is cleared again. Sending a “read angle” command by the SPI interface 1234 by the controller 1104 to the position sensor 1200 also automatically powers up the chip and starts another angle measurement. As soon as the controller 1104 has completed reading of the angle value, the INT output 1242 is cleared and a new result is stored in the angle register. The completion of the angle measurement is again indicated by setting the INT output 1242 and a corresponding flag in the status register.

Due to the measurement principle of the AS5055 position sensor 1200, only a single angle measurement is performed in very short time (˜600 ps) after each power-up sequence. As soon as the measurement of one angle is completed, the AS5055 position sensor 1200 suspends to power-down state. An on-chip filtering of the angle value by digital averaging is not implemented, as this would require more than one angle measurement and, consequently, a longer power-up time that is not desired in low-power applications. The angle jitter can be reduced by averaging of several angle samples in the controller 1104. For example, an averaging of four samples reduces the jitter by 6 dB (50%).

FIG. 13 is a section view of an end effector 2502 of the surgical instrument 10 (FIGS. 1-4) showing an I-beam 2514 firing stroke relative to tissue 2526 grasped within the end effector 2502 according to one aspect of this disclosure. The end effector 2502 is configured to operate with the surgical instrument 10 shown in FIGS. 1-4. The end effector 2502 comprises an anvil 2516 and an elongated channel 2503 with a staple cartridge 2518 positioned in the elongated channel 2503. A firing bar 2520 is translatable distally and proximally along a longitudinal axis 2515 of the end effector 2502. When the end effector 2502 is not articulated, the end effector 2502 is in line with the shaft of the instrument. An I-beam 2514 comprising a cutting edge 2509 is illustrated at a distal portion of the firing bar 2520. A wedge sled 2513 is positioned in the staple cartridge 2518. As the I-beam 2514 translates distally, the cutting edge 2509 contacts and may cut tissue 2526 positioned between the anvil 2516 and the staple cartridge 2518. Also, the I-beam 2514 contacts the wedge sled 2513 and pushes it distally, causing the wedge sled 2513 to contact staple drivers 2511. The staple drivers 2511 may be driven up into staples 2505, causing the staples 2505 to advance through tissue and into pockets 2507 defined in the anvil 2516, which shape the staples 2505.

An example I-beam 2514 firing stroke is illustrated by a chart 2529 aligned with the end effector 2502. Example tissue 2526 is also shown aligned with the end effector 2502. The firing member stroke may comprise a stroke begin position 2527 and a stroke end position 2528. During an I-beam 2514 firing stroke, the I-beam 2514 may be advanced distally from the stroke begin position 2527 to the stroke end position 2528. The I-beam 2514 is shown at one example location of a stroke begin position 2527. The I-beam 2514 firing member stroke chart 2529 illustrates five firing member stroke regions 2517, 2519, 2521, 2523, 2525. In a first firing stroke region 2517, the I-beam 2514 may begin to advance distally. In the first firing stroke region 2517, the I-beam 2514 may contact the wedge sled 2513 and begin to move it distally. While in the first region, however, the cutting edge 2509 may not contact tissue and the wedge sled 2513 may not contact a staple driver 2511. After static friction is overcome, the force to drive the I-beam 2514 in the first region 2517 may be substantially constant.

In the second firing member stroke region 2519, the cutting edge 2509 may begin to contact and cut tissue 2526. Also, the wedge sled 2513 may begin to contact staple drivers 2511 to drive staples 2505. Force to drive the I-beam 2514 may begin to ramp up. As shown, tissue encountered initially may be compressed and/or thinner because of the way that the anvil 2516 pivots relative to the staple cartridge 2518. In the third firing member stroke region 2521, the cutting edge 2509 may continuously contact and cut tissue 2526 and the wedge sled 2513 may repeatedly contact staple drivers 2511. Force to drive the I-beam 2514 may plateau in the third region 2521. By the fourth firing stroke region 2523, force to drive the I-beam 2514 may begin to decline. For example, tissue in the portion of the end effector 2502 corresponding to the fourth firing region 2523 may be less compressed than tissue closer to the pivot point of the anvil 2516, requiring less force to cut. Also, the cutting edge 2509 and wedge sled 2513 may reach the end of the tissue 2526 while in the fourth region 2523. When the I-beam 2514 reaches the fifth region 2525, the tissue 2526 may be completely severed. The wedge sled 2513 may contact one or more staple drivers 2511 at or near the end of the tissue. Force to advance the I-beam 2514 through the fifth region 2525 may be reduced and, in some examples, may be similar to the force to drive the I-beam 2514 in the first region 2517. At the conclusion of the firing member stroke, the I-beam 2514 may reach the stroke end position 2528. The positioning of firing member stroke regions 2517, 2519, 2521, 2523, 2525 in FIG. 18 is just one example. In some examples, different regions may begin at different positions along the end effector longitudinal axis 2515, for example, based on the positioning of tissue between the anvil 2516 and the staple cartridge 2518.

As discussed above and with reference now to FIGS. 10-13, the electric motor 1122 positioned within the handle assembly of the surgical instrument 10 (FIGS. 1-4) can be utilized to advance and/or retract the firing system of the shaft assembly, including the I-beam 2514, relative to the end effector 2502 of the shaft assembly in order to staple and/or incise tissue captured within the end effector 2502. The I-beam 2514 may be advanced or retracted at a desired speed, or within a range of desired speeds. The controller 1104 may be configured to control the speed of the I-beam 2514. The controller 1104 may be configured to predict the speed of the I-beam 2514 based on various parameters of the power supplied to the electric motor 1122, such as voltage and/or current, for example, and/or other operating parameters of the electric motor 1122 or external influences. The controller 1104 may be configured to predict the current speed of the I-beam 2514 based on the previous values of the current and/or voltage supplied to the electric motor 1122, and/or previous states of the system like velocity, acceleration, and/or position. The controller 1104 may be configured to sense the speed of the I-beam 2514 utilizing the absolute positioning sensor system described herein. The controller can be configured to compare the predicted speed of the I-beam 2514 and the sensed speed of the I-beam 2514 to determine whether the power to the electric motor 1122 should be increased in order to increase the speed of the I-beam 2514 and/or decreased in order to decrease the speed of the I-beam 2514. U.S. Pat. No. 8,210,411, entitled MOTOR-DRIVEN SURGICAL CUTTING INSTRUMENT, which is incorporated herein by reference in its entirety. U.S. Pat. No. 7,845,537, entitled SURGICAL INSTRUMENT HAVING RECORDING CAPABILITIES, which is incorporated herein by reference in its entirety.

Force acting on the I-beam 2514 may be determined using various techniques. The I-beam 2514 force may be determined by measuring the motor 2504 current, where the motor 2504 current is based on the load experienced by the I-beam 2514 as it advances distally. The I-beam 2514 force may be determined by positioning a strain gauge on the drive member 120 (FIG. 2), the firing member 220 (FIG. 2), I-beam 2514 (I-beam 178, FIG. 20), the firing bar 172 (FIG. 2), and/or on a proximal end of the cutting edge 2509. The I-beam 2514 force may be determined by monitoring the actual position of the I-beam 2514 moving at an expected velocity based on the current set velocity of the motor 2504 after a predetermined elapsed period T₁ and comparing the actual position of the I-beam 2514 relative to the expected position of the I-beam 2514 based on the current set velocity of the motor 2504 at the end of the period T₁. Thus, if the actual position of the I-beam 2514 is less than the expected position of the I-beam 2514, the force on the I-beam 2514 is greater than a nominal force. Conversely, if the actual position of the I-beam 2514 is greater than the expected position of the I-beam 2514, the force on the I-beam 2514 is less than the nominal force. The difference between the actual and expected positions of the I-beam 2514 is proportional to the deviation of the force on the I-beam 2514 from the nominal force. Such techniques are described in attorney docket number END8195USNP, which is incorporated herein by reference in its entirety.

FIG. 14 illustrates a block diagram of a surgical instrument 2500 programmed to control distal translation of a displacement member according to one aspect of this disclosure. In one aspect, the surgical instrument 2500 is programmed to control distal translation of a displacement member 1111 such as the I-beam 2514. The surgical instrument 2500 comprises an end effector 2502 that may comprise an anvil 2516, an I-beam 2514 (including a sharp cutting edge 2509), and a removable staple cartridge 2518. The end effector 2502, anvil 2516, I-beam 2514, and staple cartridge 2518 may be configured as described herein, for example, with respect to FIGS. 1-13.

The position, movement, displacement, and/or translation of a liner displacement member 1111, such as the I-beam 2514, can be measured by the absolute positioning system 1100, sensor arrangement 1102, and position sensor 1200 as shown in FIGS. 10-12 and represented as position sensor 2534 in FIG. 14. Because the I-beam 2514 is coupled to the longitudinally movable drive member 120, the position of the I-beam 2514 can be determined by measuring the position of the longitudinally movable drive member 120 employing the position sensor 2534. Accordingly, in the following description, the position, displacement, and/or translation of the I-beam 2514 can be achieved by the position sensor 2534 as described herein. A control circuit 2510, such as the control circuit 700 described in FIGS. 5A and 5B, may be programmed to control the translation of the displacement member 1111, such as the I-beam 2514, as described in connection with FIGS. 10-12. The control circuit 2510, in some examples, may comprise one or more microcontrollers, microprocessors, or other suitable processors for executing instructions that cause the processor or processors to control the displacement member, e.g., the I-beam 2514, in the manner described. In one aspect, a timer/counter circuit 2531 provides an output signal, such as elapsed time or a digital count, to the control circuit 2510 to correlate the position of the I-beam 2514 as determined by the position sensor 2534 with the output of the timer/counter circuit 2531 such that the control circuit 2510 can determine the position of the I-beam 2514 at a specific time (t) relative to a starting position. The timer/counter circuit 2531 may be configured to measure elapsed time, count external evens, or time external events.

The control circuit 2510 may generate a motor set point signal 2522. The motor set point signal 2522 may be provided to a motor controller 2508. The motor controller 2508 may comprise one or more circuits configured to provide a motor drive signal 2524 to the motor 2504 to drive the motor 2504 as described herein. In some examples, the motor 2504 may be a brushed DC electric motor, such as the motor 82, 714, 1120 shown in FIGS. 1, 5B, 10. For example, the velocity of the motor 2504 may be proportional to the motor drive signal 2524. In some examples, the motor 2504 may be a brushless direct current (DC) electric motor and the motor drive signal 2524 may comprise a pulse-width-modulated (PWM) signal provided to one or more stator windings of the motor 2504. Also, in some examples, the motor controller 2508 may be omitted and the control circuit 2510 may generate the motor drive signal 2524 directly.

The motor 2504 may receive power from an energy source 2512. The energy source 2512 may be or include a battery, a super capacitor, or any other suitable energy source 2512. The motor 2504 may be mechanically coupled to the I-beam 2514 via a transmission 2506. The transmission 2506 may include one or more gears or other linkage components to couple the motor 2504 to the I-beam 2514. A position sensor 2534 may sense a position of the I-beam 2514. The position sensor 2534 may be or include any type of sensor that is capable of generating position data that indicates a position of the I-beam 2514. In some examples, the position sensor 2534 may include an encoder configured to provide a series of pulses to the control circuit 2510 as the I-beam 2514 translates distally and proximally. The control circuit 2510 may track the pulses to determine the position of the I-beam 2514. Other suitable position sensor may be used, including, for example, a proximity sensor. Other types of position sensors may provide other signals indicating motion of the I-beam 2514. Also, in some examples, the position sensor 2534 may be omitted. Where the motor 2504 is a stepper motor, the control circuit 2510 may track the position of the I-beam 2514 by aggregating the number and direction of steps that the motor 2504 has been instructed to execute. The position sensor 2534 may be located in the end effector 2502 or at any other portion of the instrument.

The control circuit 2510 may be in communication with one or more sensors 2538. The sensors 2538 may be positioned on the end effector 2502 and adapted to operate with the surgical instrument 2500 to measure the various derived parameters such as gap distance versus time, tissue compression versus time, and anvil strain versus time. The sensors 2538 may comprise a magnetic sensor, a magnetic field sensor, a strain gauge, a pressure sensor, a force sensor, an inductive sensor such as an eddy current sensor, a resistive sensor, a capacitive sensor, an optical sensor, and/or any other suitable sensor for measuring one or more parameters of the end effector 2502. The sensors 2538 may include one or more sensors.

The one or more sensors 2538 may comprise a strain gauge, such as a micro-strain gauge, configured to measure the magnitude of the strain in the anvil 2516 during a clamped condition. The strain gauge provides an electrical signal whose amplitude varies with the magnitude of the strain. The sensors 2538 may comprise a pressure sensor configured to detect a pressure generated by the presence of compressed tissue between the anvil 2516 and the staple cartridge 2518. The sensors 2538 may be configured to detect impedance of a tissue section located between the anvil 2516 and the staple cartridge 2518 that is indicative of the thickness and/or fullness of tissue located therebetween.

The sensors 2538 may be is configured to measure forces exerted on the anvil 2516 by the closure drive system 30. For example, one or more sensors 2538 can be at an interaction point between the closure tube 260 (FIG. 3) and the anvil 2516 to detect the closure forces applied by the closure tube 260 to the anvil 2516. The forces exerted on the anvil 2516 can be representative of the tissue compression experienced by the tissue section captured between the anvil 2516 and the staple cartridge 2518. The one or more sensors 2538 can be positioned at various interaction points along the closure drive system 30 (FIG. 2) to detect the closure forces applied to the anvil 2516 by the closure drive system 30. The one or more sensors 2538 may be sampled in real time during a clamping operation by a processor as described in FIGS. 5A-5B. The control circuit 2510 receives real-time sample measurements to provide analyze time based information and assess, in real time, closure forces applied to the anvil 2516.

A current sensor 2536 can be employed to measure the current drawn by the motor 2504. The force required to advance the I-beam 2514 corresponds to the current drawn by the motor 2504. The force is converted to a digital signal and provided to the control circuit 2510.

Using the physical properties of the instruments disclosed herein in connection with FIGS. 1-14, and with reference to FIG. 14, the control circuit 2510 can be configured to simulate the response of the actual system of the instrument in the software of the controller. A displacement member can be actuated to move an I-beam 2514 in the end effector 2502 at or near a target velocity. The surgical instrument 2500 can include a feedback controller, which can be one of any feedback controllers, including, but not limited to a PID, a State Feedback, LQR, and/or an Adaptive controller, for example. The surgical instrument 2500 can include a power source to convert the signal from the feedback controller into a physical input such as case voltage, pulse width modulated (PWM) voltage, frequency modulated voltage, current, torque, and/or force, for example.

The actual drive system of the surgical instrument 2500 is configured to drive the displacement member, cutting member, or I-beam 2514, by a brushed DC motor with gearbox and mechanical links to an articulation and/or knife system. Another example is the electric motor 2504 that operates the displacement member and the articulation driver, for example, of an interchangeable shaft assembly. An outside influence is an unmeasured, unpredictable influence of things like tissue, surrounding bodies and friction on the physical system. Such outside influence can be referred to as drag which acts in opposition to the electric motor 2504. The outside influence, such as drag, may cause the operation of the physical system to deviate from a desired operation of the physical system.

Before explaining aspects of the surgical instrument 2500 in detail, it should be noted that the example aspects are not limited in application or use to the details of construction and arrangement of parts illustrated in the accompanying drawings and description. The example aspects may be implemented or incorporated in other aspects, variations and modifications, and may be practiced or carried out in various ways. Further, unless otherwise indicated, the terms and expressions employed herein have been chosen for the purpose of describing the example aspects for the convenience of the reader and are not for the purpose of limitation thereof. Also, it will be appreciated that one or more of the following-described aspects, expressions of aspects and/or examples, can be combined with any one or more of the other following-described aspects, expressions of aspects and/or examples.

Various example aspects are directed to a surgical instrument 2500 comprising an end effector 2502 with motor-driven surgical stapling and cutting implements. For example, a motor 2504 may drive a displacement member distally and proximally along a longitudinal axis of the end effector 2502. The end effector 2502 may comprise a pivotable anvil 2516 and, when configured for use, a staple cartridge 2518 positioned opposite the anvil 2516. A clinician may grasp tissue between the anvil 2516 and the staple cartridge 2518, as described herein. When ready to use the instrument 2500, the clinician may provide a firing signal, for example by depressing a trigger of the instrument 2500. In response to the firing signal, the motor 2504 may drive the displacement member distally along the longitudinal axis of the end effector 2502 from a proximal stroke begin position to a stroke end position distal of the stroke begin position. As the displacement member translates distally, an I-beam 2514 with a cutting element positioned at a distal end, may cut the tissue between the staple cartridge 2518 and the anvil 2516.

In various examples, the surgical instrument 2500 may comprise a control circuit 2510 programmed to control the distal translation of the displacement member, such as the I-beam 2514, for example, based on one or more tissue conditions. The control circuit 2510 may be programmed to sense tissue conditions, such as thickness, either directly or indirectly, as described herein. The control circuit 2510 may be programmed to select a firing control program based on tissue conditions. A firing control program may describe the distal motion of the displacement member. Different firing control programs may be selected to better treat different tissue conditions. For example, when thicker tissue is present, the control circuit 2510 may be programmed to translate the displacement member at a lower velocity and/or with lower power. When thinner tissue is present, the control circuit 2510 may be programmed to translate the displacement member at a higher velocity and/or with higher power.

In some examples, the control circuit 2510 may initially operate the motor 2504 in an open-loop configuration for a first open-loop portion of a stroke of the displacement member. Based on a response of the instrument 2500 during the open-loop portion of the stroke, the control circuit 2510 may select a firing control program. The response of the instrument may include, a translation distance of the displacement member during the open-loop portion, a time elapsed during the open-loop portion, energy provided to the motor 2504 during the open-loop portion, a sum of pulse widths of a motor drive signal, etc. After the open-loop portion, the control circuit 2510 may implement the selected firing control program for a second portion of the displacement member stroke. For example, during the closed loop portion of the stroke, the control circuit 2510 may modulate the motor 2504 based on translation data describing a position of the displacement member in a closed-loop manner to translate the displacement member at a constant velocity.

FIG. 15 illustrates a diagram 2580 plotting two example displacement member strokes executed according to one aspect of this disclosure. The diagram 2580 comprises two axes. A horizontal axis 2584 indicates elapsed time. A vertical axis 2582 indicates the position of the I-beam 2514 between a stroke begin position 2586 and a stroke end position 2588. On the horizontal axis 2584, the control circuit 2510 may receive the firing signal and begin providing the initial motor setting at t₀. The open-loop portion of the displacement member stroke is an initial time period that may elapse between t₀ and t₁.

A first example 2592 shows a response of the surgical instrument 2500 when thick tissue is positioned between the anvil 2516 and the staple cartridge 2518. During the open-loop portion of the displacement member stroke, e.g., the initial time period between t₀ and t₁, the I-beam 2514 may traverse from the stroke begin position 2586 to position 2594. The control circuit 2510 may determine that position 2594 corresponds to a firing control program that advances the I-beam 2514 at a selected constant velocity (Vslow), indicated by the slope of the example 2592 after t₁ (e.g., in the closed loop portion). The control circuit 2510 may drive I-beam 2514 to the velocity Vslow by monitoring the position of I-beam 2514 and modulating the motor set point 2522 and/or motor drive signal 2524 to maintain Vslow. A second example 2590 shows a response of the surgical instrument 2500 when thin tissue is positioned between the anvil 2516 and the staple cartridge 2518.

During the initial time period (e.g., the open-loop period) between t₀ and t₁, the I-beam 2514 may traverse from the stroke begin position 2586 to position 2596. The control circuit may determine that position 2596 corresponds to a firing control program that advances the displacement member at a selected constant velocity (Vfast). Because the tissue in example 2590 is thinner than the tissue in example 2592, it may provide less resistance to the motion of the I-beam 2514. As a result, the I-beam 2514 may traverse a larger portion of the stroke during the initial time period. Also, in some examples, thinner tissue (e.g., a larger portion of the displacement member stroke traversed during the initial time period) may correspond to higher displacement member velocities after the initial time period.

The disclosure now turns to a closed loop feedback system to provide velocity control of a displacement member. The closed loop feedback system adjusts the velocity of the displacement member based on a measurement of actual time over a specified number of shaft rotations. In one aspect, the closed loop feedback system comprises two phases. A start phase defined as the start of a firing stroke followed by a dynamic firing phase while the I-beam 2514 advances distally during the firing stroke. FIGS. 16A and 16B show the I-beam 2514 positioned at the start phase of the firing stroke. FIG. 16A illustrates an end effector 2502 comprising a firing member 2520 coupled to an I-beam 2514 comprising a cutting edge 2509. The anvil 2516 is in the closed position and the I-beam 2514 is located in a proximal or parked position 10002 at the bottom of the closure ramp 10006. The parked position 10002 is the position of the I-beam 2514 prior to traveling up the anvil 2516 closure ramp 10006 to the top of the ramp 10006 to the T-slot 10008 after a predetermined number of shaft rotations. A top pin 10080 is configured to engage a T-slot 10008 and a lockout pin 10082 is configured to engage a latch feature 10084.

In FIG. 16B the I-beam 2514 is located in a target position 10004 at the top of the ramp 10006 with the top pin 10080 engaged in the T-slot 10008. As shown in FIGS. 14, 16A, and 16B and , in traveling from the parked position 10002 to the target position 10004, the I-beam 2514 travels a distance indicated as X, in the horizontal distal direction after a predetermined number of shaft rotations. During the start phase, the velocity of the I-beam 2514 is set to a predetermined initial velocity Φ₀ rotations per seconds. A control circuit 2510 measures the actual time t₀ that it takes the I-beam 2514 to travel up the ramp 10006 from the parked position 10002 to the target position 10004 at the initial velocity Φ₀ rotations per second. In one aspect, the horizontal distance is in the range of 5 mm to 10 mm and in one example is 7.4 mm and the initial velocity Φ₀=5 rotations per second. As described in more detail below, the actual time t₀ is used to set the command velocity of the I-beam 2514 in terms of rotations per second of the shaft to slow, medium, or fast in the subsequent staple cartridge zone Z as the I-beam 2514 advances distally. The number of zones may depend on the length/size of the staple cartridge (e.g., 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, >60 mm). The command velocity or set velocity is the velocity of the motor 2504 that is applied to the motor 2504 by the control circuit 2510 and motor control 2508 in order effect a desired velocity of the I-beam 2514. In one aspect, the velocity is determined based on rotations of the shaft of the motor 2504 in terms of rotations per second. The actual velocity of the I-beam 2514 is determined by the control circuit 2510 by measuring the actual time t₀ with the timer/counter 2531 circuit that it takes the I-beam 2514 to traverse a specified or fixed distance provided by the position sensor 2534 based on a set rotation interval assuming, in one example, of 60 threads per inch. In accordance with one aspect of the present disclosure, the closed loop feedback control system of the surgical instrument measures the actual time t₀ it takes the I-beam 2514, or a displacement member, to travel a predetermined fixed distance or rotation interval X_(n) after a predetermined set of rotation interval of the motor shaft assuming a 60 threads per inch. A predetermined fixed distance or rotation interval X_(n) is defined for each zone (e.g., Z₁, Z₂, Z₃. . . Z_(n)).

FIG. 17 illustrates a screw drive system 10470 that may be employed with the surgical instrument 10 (FIG. 1) according to one aspect of this disclosure. In one aspect, the longitudinally movable drive member 120 (FIG. 2) may be replaced with the screw drive (sometime referred to as a nut drive) system 10470. The screw drive system 10470 comprises a leadscrew 10472, ball screw or other mechanical linear actuator, adapted and configured to couple to the shaft 10474 of the motor 82 (FIG. 2) via the drive gear 10478 to translate rotational motion to linear motion. The leadscrew 10472 is coupled to the firing member 220 via a nut 1476. The firing member 220 is coupled to firing bar 172, which is coupled to the I-beam 178 as shown and described with reference to FIGS. 2-4. The drive gear 10478, which is driven by the shaft 1474 of the motor 82 is adapted to rotate the screw drive system 10470.

The screw drive system 10470 comprises a leadscrew 10472 and a nut 10476, also known as a power screw or translation screw, and is adapted to couple to the shaft 10474 of the motor 82 via the drive gear 10478 to translate turning motion of the shaft 10474 of the motor 82 into linear motion of the displacement member, such as the I-beam 2514, for example, which is coupled to the nut 10476. The leadscrew 10472 threads are in sliding contact with their counterparts within the nut 10476 such that as the leadscrew 10472 rotates the nut 10476 translates forward and backward according to the rotation of the drive gear 10478 as indicated. A ball screw also may be used for low friction application. In a ball screw, a threaded shaft provides a helical raceway for ball bearings which act as a precision screw. As well as being able to apply or withstand high thrust loads, they can do so with minimum internal friction. Close tolerances make it suitable for use in high precision applications. The ball assembly acts as the nut while the threaded shaft is the screw. The screw drive system 10470, such as the leadscrew 10472 and nut 10476, or ball screw drive, may include a threaded shaft having 60 threads per inch such that a 60 mm staple cartridge can be traversed in approximately 142 rotations of the motor shaft. For example, one rotation of the threaded shaft of the leadscrew 10472 advances the nut 10476 and the displacement member 1 inch (25.4 mm). A 60 mm cartridge is 2.36 inches long and requires ˜142 rotations of the leadscrew 10472 to advance the nut 10476 and the displacement member the full 60 mm stroke if the re is a 1:1 ratio between the rotation of the shaft 10474 and the rotation of the leadscrew 10472. Other ratios using gear reduction assemblies may be adapted without limitation. The rotation of the shaft 10474 can be measured by a position sensor arrangement comprising one or more magnets and one or more Hall effect sensors to measure the rotation of the shaft 104747 and provide the shaft rotation signals to the control circuit.

In one aspect, with reference to FIG. 17 and also FIGS. 2-4 and 10-12, the rotations of the shaft 10474 of the motor 82 (FIG. 2) or 1116 (FIG. 10) can be measured by measuring the rotation of the shaft 1214 (FIG. 11) coupled to the drive gear 86 (FIG. 2) using the absolute positioning system 1100 (FIGS. 10 and 12) and position sensor 1200 (FIGS. 11, 12). Wth reference to FIG. 12, the position sensor 1200 for the absolute positioning system 1100 comprising a magnetic rotary absolute positioning system can be employed to measure magnetic rotary position of the shaft of the motor. The position sensor 1200 is interfaced with the controller 1104 to provide an absolute positioning system 1100. Additional details of absolute positioning system 1100 and position sensor 1200 are described above in reference to FIG. 12 and for expedience will not be repeated here.

Turning now to FIG. 18, there is illustrated an I-beam 2514 firing stroke as a chart 9009 aligned with the end effector 2502 according to one aspect of this disclosure. As shown, the initial zone (Z₀), or base zone, is defined as the distance traveled by the I-beam 2514 from the parked position 10002 to the target position 10004. The measured time T₀ is the time it takes the I-beam 2514 to travel up the closure ramp 10006 to the target position 10004 at an initial set velocity Φ₀ rotations/sec. The measured times T₁-T5 are reference periods of time for traversing the corresponding zones Z₁-Z₅, respectively. The displacement of the I-beam 2514 in zone Z₀ is ⊖₀ rotations. The period T₀, the time it takes for the I-beam 2514 to travel over a distance ⊖₀. is used to set the command velocity in the subsequent zone Z₁.

With reference now to FIGS. 14-18, at the start phase, e.g., at the beginning of a firing stroke, the control circuit 2510 is configured to initiate firing the displacement member, such as the I-beam 2514, at a predetermined velocity Φ₀ (e.g., 5 rotations/sec). During the start phase, the control circuit 2510 is configured to monitor the position of the I-beam 2514 and measure the time t₀ (sec) it takes for the I-beam 2514 to travel from the I-beam 2514 parked position 10002 to the I-beam 2514 target position 10004, either to the top of the anvil 2516 closure ramp 10006, or at the end of a low power mode of operation. Time t₀ in the initial zone 10010 is used by the control circuit 2510 to determine the firing velocity of the I-beam 2514 through the first zone Z₁. For example, in one aspect, if time t₀ is <0.9 sec the velocity Φ₁ may be set to fast and if time t₀≥0.9 sec the velocity Φ₁ may be set to medium. Faster or slower times may be selected based on the length of the staple cartridge 2518. The actual time t₁-t5 that it takes the I-beam 2514 to traverse a corresponding zone Z₁ to Z5 is measured at a corresponding set rotation displacement δ₁-δ5 and is compared to a corresponding reference time period T₁-T₅. In various aspects, if a lockout condition is encountered, the motor 2504 will stall before the I-beam 2514 reaches the target position 10004. When this condition occurs, the surgical instrument display indicates the instrument status and may issue a stall warning. The display also may indicate a speed selection.

During the dynamic firing phase, the surgical instrument enters the dynamic firing phase, where the control circuit 2510 is configured to monitor the rotation interval δ_(n) of the I-beam 2514 and measure the time t_(n) that it takes the I-beam 2514 to travel from the beginning of a zone to the end of a zone (e.g., a total distance of 12 rotations or 23 rotations). In FIG. 17, the reference time T₁ is the time taken by the I-beam 2514 to travel from the beginning of zone Z₁ to the end of zone Z₁ at a set velocity Φ₁. Likewise, the reference time T₂ is the time it takes the I-beam 2514 to travel from the beginning of zone Z₂ to the end of zone Z₂ at a set velocity Φ₂, and so on. Table 1 shows zones that may be defined for staple cartridges 2518 of various sizes.

TABLE 1 Defined Zones For Staple Cartridges Of Various Sizes Staple Zones Cartridge Z₁ Z₂ Z₃ Z₄ Z₅ Z₆ 35 mm 0-12 12-35 35-59 >59 N/A N/A rota- rota- rota- rota- tions tions tions tions 40-45 mm 0-12 12-35 35-59 59-82 >82 N/A rota- rota- rota- rota- rota- tions tions tions tions tions 55-60 mm 0-12 12-35 35-59 59-82 82-106 >106 rota- rota- rota- rota- rota- rota- tions tions tions tions tions tions

For staple cartridges 2518 over 60 mm, the pattern continues, but the last 10-15 mm continues at a command or indicated velocity of the previous zone pending other interventions for end of stroke, among others. At the end of each zone, the actual time t_(n) it took the I-beam 2514 to pass through the zone is compared to the values in other tables (e.g., Tables 2-5 below) to determine how to set the command velocity for the next zone. The command velocity is updated for the next zone and the process continues. Whenever the command velocity is updated, the next zone will not be evaluated. The end of stroke is handled in accordance with a predetermined protocol/algorithm of the surgical instrument including limit switches, controlled deceleration, etc. At the end of stroke, the I-beam 2514 is returned to the initial I-beam park position 10002 at the fast speed. End of return stroke (returning to the parked position 10002) is handled in accordance with the protocol/algorithm of the surgical instrument. Other zones may be defined without limitation.

TABLE 2 Time To Travel Through Zones At Specified Command Velocity For Various Dynamic Firing Zones Time (sec) to Travel Through Zone at Dynamic Firing Zone Specified Command Velocity (rotations) Fast Medium Slow First Zone (Θ₁ rotations) t < t₁ t₁ < t < t₂ t > t₂ Intermediate Zones (Θ₂ rotations) t < t₃ t₃ < t < t₄ t > t₄ Last Measured Zone (Θ₃ rotations) t < t₅ t₅ < t < t₆ t > t₆

TABLE 3 Non-limiting Examples Of Time To Travel Through Zones At Specified Command Velocity For Various Dynamic Firing Zones Time (sec) to Travel Through Zone Dynamic Firing Zone at Specified Command Velocity (rotations) Fast Medium Slow First Zone (5 mm long) t < 0.5 0.5 < t < 0.6 t > 0.6 Intermediate Zones t < 0.9 0.9 < t < 1.1 t > 1.1 (10 mm long) Last Measured Zone t < 1.0 1.0 < t < 1.3 t > 1.3 (10 mm long)

TABLE 4 Algorithm To Set Velocity Based On Time To Travel Up Ramp Algorithm t_(a) (sec) t_(b) (sec) If time t (sec) for I-beam t₁ < t < t₂ t > t₂ to t₃ to travel up ramp is . . . Then initial velocity V of V₁ (mm/sec) V₂ (mm/sec) I-beam in T-slot is . . . And automatic velocity is set at . . . FAST MEDIUM

TABLE 5 Non-limiting Example Of Algorithm To Set Velocity Based On Time To Travel Up Ramp Algorithm t_(a) (sec) t_(b) (sec) If time t (sec) for I-beam to travel up ramp is . . . t < 0.9 t ≥ 0.9 Then initial velocity of I-beam in T-slot is . . . 30 mm/sec 12 mm/sec And automatic velocity is set at . . . FAST MEDIUM

In one aspect, Tables 1-5 may be stored in memory of the surgical instrument. The Tables 1-5 may be stored in memory in the form of a look-up table (LUT) such that the control circuit 2510 can retrieve the values and control the command velocity of the I-beam 2514 in each zone based on the values stored in the LUT.

FIG. 19 is a graphical depiction 10100 comparing the I-beam 2514 stroke rotation interval δ_(n) as a function of time 10102 (top graph) and expected force-to-fire the I-beam 2514 as a function of time 10104 (bottom graph) according to one aspect of this disclosure. Referring to the top graph 10102, the horizontal axis 10106 represents time (t) in seconds (sec) from 0-1.00X, where X is a scaling factor. For example, in one aspect, X=6 and the horizontal axis 10106 represents time from 0-6 sec. The vertical axis 10108 represents displacement (δ) of the I-beam 2514 in millimeters (mm). The rotation interval δ₁ represents the I-beam 2615 stroke 10114 or displacement at the top of the ramp 10006 (FIGS. 16A, 16B) for thin tissue and medium thick tissue. The time for the I-beam 2514 to reach the top of ramp stroke 10114 for thin tissue is t₁ and the time for the I-beam 2514 to reach the top of ramp stroke 10114 for medium thick tissue is t₂. As shown, t₁<t₂, such that it takes less time for the I-beam 2514 to reach the top of the ramp stroke 10114 for thin tissue as it takes for medium or thick tissue. In one example, the top of ramp stroke 10114 rotation interval δ₁ is about 4.1 mm (01.60 inches) and the time t₁ is less than 0.9 sec (t₁<0.9 sec) and the time t₂ is greater than 0.9 sec but less than 1.8 sec (0.9<t₂<1.8 sec). Accordingly, with reference also to Table 5, the velocity to reach the top of ramp stroke 10114 is fast for thin tissue and medium for medium thick tissue.

Turning now to the bottom graph 10104, the horizontal axis 10110 represents time (t) in seconds (sec) and has the same scale of the horizontal axis 10106 of the top graph 10102. The vertical axis 10112, however, represents expected force to fire (F) the I-beam 2514 in newtons (N) for thin tissue force to fire graph 10116 and medium thick tissue force to fire graph 10118. The thin tissue force to fire graph 10116 is lower than medium thick tissue force to fire graph 10118. The peak force F₁ for the thin tissue force to fire graph 10116 is lower than the peak force F₂ for the medium thick tissue to fire graph 10118. Also, with reference to the top and bottom graphs 10102, 10104, the initial velocity of the I-beam 2514 in zone Z₀ can be determined based on estimated tissue thickness. As shown by the thin tissue force to fire graph 10116, the I-beam 2514 reaches the peak force F₁ top of ramp stroke 10114 at a fast initial velocity (e.g., 30 mm/sec) and as shown by the medium thick tissue force to fire graph 10118, the I-beam 2514 reaches the peak force F₂ top of ramp stroke 10114 at a medium initial velocity (e.g., 12 mm/sec). Once the initial velocity in zone Z₀ is determined, the control circuit 2510 can set the estimated velocity of the I-beam 2514 in zone Z₁, and so on.

FIG. 20 is a graphical depiction 10200 comparing tissue thickness as a function of set rotation interval of I-beam stroke 10202 (top graph), force to fire as a function of set rotation interval of I-beam stroke 10204 (second graph from the top), dynamic time checks as a function of set rotation interval of I-beam stroke 10206 (third graph from the top), and set velocity of I-beam as a function of set rotation interval of I-beam stroke 10208 (bottom graph) according to one aspect of this disclosure. The horizontal axis 10210 for each of the graphs 10202, 10204, 10206, 10208 represents set rotation interval of the shaft of the motor 2504 for a 60 mm staple cartridge, for example. The motor 2504 shaft rotations correspond to a displacement of the displacement member, such as the I-beam 2514, for example. In one example, a 60 mm cartridge 2518 can be traversed by the I-beam 2514 in about 142 rotations of the motor 2504 shaft with a 60 threads per inch screw drive. With reference also to Table 1, the horizontal axis 10210 has been marked to identify the defined zones Z₁-Z₆ for a 60 mm staple cartridge. As indicated in Table 1, the defined zones may be marked for staple cartridges of various sizes. The horizontal axis 10210 is marked from 0 to 142 rotations for a 60 mm cartridge and 60 threads per inch leadscrew drive. With reference also to FIG. 14, in accordance with the present disclosure, the control circuit 2510 samples or measures the elapsed time from the timer/counter circuit 2531 for a number of motor 2504 shaft rotation intervals corresponding to the displacement of the I-beam 2514 traversing the staple cartridge 2518 during the firing stroke. At set rotation intervals δ_(n), 12 rotations, 23 rotations, or other suitable number of shaft rotations for example, received from the position sensor 2534, the control circuit 2510 samples or measures the elapsed time t_(n) taken by the I-beam 2514 to travel a distance corresponding to the fixed rotation intervals δ_(n). For example, a leadscrew with 60 threads per inch corresponds to 0.42 mm per rotation. Thus, 12 rotations of the motor 2504 shaft correspond to a linear displacement of 5.04 mm (˜5 mm) and 23 rotations of the motor 2504 shaft corresponds to a displacement of 9.66 mm (˜10 mm), for example. In this manner, the control circuit 2510 can determine the actual velocity of the I-beam 2514 and compare the actual velocity to the estimated velocity and make any necessary adjustments to the motor 2504 velocity.

The tissue thickness graph 10202 shows a tissue thickness profile 10220 along the staple cartridge 2518 and an indicated thickness 10221 as shown by the horizontal dashed line. The force to fire graph 10204 shows the force to fire profile 10228 along the staple cartridge 2518. The force to fire 10230 remains relatively constant while the tissue thickness 10222 remains below the indicated thickness 10221 as the I-beam 2514 traverse zones Z₁ and Z₂. As the I-beam 2514 enters zone Z₃, the tissue thickness 10224 increases and the force to fire also increase while the I-beam 2514 traverses the thicker tissue in zones Z₃, Z₄, and Z₅. As the I-beam 2514 exits zone Z5 and enters zone Z₆, the tissue thickness 10226 decrease and the force to fire 10234 also decreases.

Wth reference now to FIGS. 14, 16-20 and Tables 2-3, the velocity Φ₁ in zone Z₁ is set to the command velocity Φ₀ in rotations per second determined by the control circuit 2510 in zone Z₀. which is based on the time it takes the I-beam 2514 to travel to the top of the ramp 10006 in zone Z₀ as discussed in reference to FIGS. 16A, 16B, and 18. Turning also to the graphs 10206, 10208 in FIG. 19, the initial set velocity Φ₀ was set to Medium and thus the set velocity Φ₁ in zone Z₁ is set to Medium such that Φ₁=Φ₀.

At set rotation position δ₁ (e.g., 12 rotations [5.04 mm] for a 60 mm staple cartridge and 60 threads per inch leadscrew), as the I-beam 2514 exits zone Z₁ and enters zone Z₂, the control circuit 2510 measures the actual time t₁ that it takes the I-beam 2514 to travel a set distance during the set rotation interval ⊖₁ (12 rotations, 5.04 mm) and determines the actual velocity of the I-beam 2514. With reference to graphs 10206 and 10208 in FIG. 19, at set rotation position δ₁, the actual time t₁ it takes the I-beam 2514 to travel a set distance during the set rotation interval ⊖₁ is t₁=0.55 sec. According to Table 3, an actual travel time t₁=0.55 sec in zone Z₁ requires the command or set velocity Φ₂ in zone Z₂ to be set to Medium. Accordingly, the control circuit 2510 does not reset the command velocity for zone Z₂ and maintains it at Medium.

At set rotation position δ₂ (e.g., 35 rotations [14.7 mm] for a 60 mm staple cartridge and 60 threads per inch leadscrew), as the I-beam 2514 exits zone Z₂ and enters zone Z₃, the control circuit 2510 measures the actual time t₂ it takes the I-beam 2514 to travel a set distance during the set rotation interval ⊖₂ (23 rotations, 9.66 mm) and determines the actual velocity of the I-beam 2514. With reference to graphs 10606 and 10608 in FIG. 19, at set rotation position δ₂, the actual time t₂ it takes the I-beam 2514 to travel a set distance during the set rotation interval ⊖₂ is t₂=0.95 sec. According to Table 3, an actual travel time t₂=0.95 sec in zone Z₂ requires the command or set velocity Φ₃ in zone Z₃ to be set to Medium. Accordingly, the control circuit 2510 does not reset the command velocity for zone Z₃ and maintains it at Medium.

At set rotation position δ₃ (e.g., 59 rotations [24.78 mm] for a 60 mm staple cartridge and 60 threads per inch leadscrew), as the I-beam 2514 exits zone Z₃ and enters zone Z₄, the control circuit 2510 measures the actual time t₃ it takes the I-beam 2514 to travel a set distance during the set rotation interval ⊖₃ (23 rotations, 9.66 mm) and determines the actual velocity of the I-beam 2514. With reference to graphs 10606 and 10608 in FIG. 19, at set rotation position δ₃, the actual time t₃ it takes the I-beam 2514 to travel a set distance during the set rotation interval ⊖₃ is t₃=1.30 sec. According to Table 3, an actual travel time t₃=1.30 sec in zone Z₃ requires the command or set velocity Φ₄ in zone Z₄ to be set to Slow. This is because the actual travel time of 1.3 sec is greater than 1.10 sec and is outside the previous range. Accordingly, the control circuit 2510 determines that the actual I-beam 2514 velocity in zone Z₃ was slower than expected due to external influences such as thicker tissue than expected as shown in tissue region 10224 in graph 10202. Accordingly, the control circuit 2510 resets the command velocity Φ₄ in zone Z₄ from Medium to Slow.

In one aspect, the control circuit 2510 may be configured to disable velocity reset in a zone following a zone in which the velocity was reset. Stated otherwise, whenever the velocity is updated in a present zone the subsequent zone will not be evaluated. Since the velocity was updated in zone Z₄, the time it takes the I-beam 2514 to traverse zone Z₄ will not be measured at the end of zone Z₄ at the set rotation distance δ₄ (e.g., 82 rotations [34.44 mm] for a 60 mm staple cartridge). Accordingly, the velocity in zone Z5 will remain the same as the velocity in zone Z₄ and dynamic time measurements resume at set rotation position δ5 (e.g., 106 rotations [44.52 mm] for a 60 mm staple cartridge and 60 threads per inch leadscrew).

At set rotation position δ5 (e.g., 106 rotations [44.52 mm] for a 60 mm staple cartridge and 60 threads per inch leadscrew) as the I-beam 2514 exits zone Z5 and enters zone Z₆, the control circuit 2510 measures the actual time t5 it takes the I-beam 2514 to travel a set distance during the set rotation interval ⊖5 (23 rotations, 9.75 mm) and determines the actual velocity of the I-beam 2514. With reference to graphs 10606 and 10608 in FIG. 19, at set rotation position δ₅, the actual time t5 it takes the I-beam 2514 to travel a set distance during the set rotation interval ⊖5 is t₅=0.95 sec. According to Table 3, an actual travel time of t₅=0.95 sec in zone Z5 requires the command or set velocity Φ₆ in zone Z₆ to be set to High. This is because the actual travel time of 0.95 sec is less than 1.00 sec is outside the previous range. Accordingly, the control circuit 2510 determines that the actual velocity of the I-beam 2514 in zone Z5 was faster than expected due to external influences such as thinner tissue than expected as shown in tissue region 10626 in graph 10602. Accordingly, the control circuit 2510 resets the command velocity Φ₆ in zone Z₆ from Slow to High.

FIG. 21 is a graphical depiction 10300 of force to fire as a function of time comparing slow, medium and fast I-beam 2514 displacement velocities according to one aspect of this disclosure. The horizontal axis 10302 represents time t (sec) that it takes an I-beam to traverse a staple cartridge. The vertical axis 10304 represents force to fire F (N). The graphical depiction shows three separate force to fire curves versus time. A first force to fire curve 10312 represents an I-beam 2514 (FIG. 14) traversing through thin tissue 10306 at a fast velocity and reaching a maximum force to fire F₁ at the top of the ramp 10006 (FIG. 16B) at t₁. In one example, a fast traverse velocity for the I-beam 2514 is ˜30 mm/sec (˜71 rotations/sec). A second force to fire curve 10314 represents an I-beam 2514 traversing through medium tissue 10308 at a medium velocity and reaching a maximum force to fire F₂ at the top of the ramp 10006 at t₂, which is greater than t₁. In one example, a medium traverse velocity for the I-beam 2514 is ˜12 mm/sec (˜29 rotations/sec). A third force to fire curve 10316 represents an I-beam 2514 traversing through thick tissue 10310 at a slow velocity and reaching a maximum force to fire F₃ at the top of the ramp 9006 at t₃, which is greater than t₂. In one example, a slow traverse velocity for the I-beam 2514 is ˜9 mm/sec (˜21 rotations/sec).

FIG. 22 is a logic flow diagram of a process 10400 depicting a control program or logic configuration for controlling command velocity in an initial firing stage according to one aspect of this disclosure. Wth reference also to FIGS. 14 and 16-20, the control circuit 2510 determines 10402 the reference position of the displacement member, such as the I-beam 2514, based on the number of rotations of the motor 2504 shaft and the number threads per mm or inch of the leadscrew. As discussed previously, a leadscrew having 60 threads per inch advances the displacement member 0.42 mm per rotation of the shaft. The position information based on the shaft rotation information is provided by the position sensor 2534. In the I-beam 2514 example, the reference position is the proximal or parked position 10002 at the bottom of the closure ramp 10006 as shown in FIG. 16B. Once the reference position is determined 10402, the control circuit 2510 and motor control 2508 set the command velocity of the motor 2504 to a predetermined command velocity Φ₀ and initiates 10404 firing the displacement member (e.g., I-beam 2514) at the predetermined command velocity Φ₀ for the initial or base zone Z₀. In one example, the initial predetermined command velocity Φ₀ is ˜12 mm/sec (29 rotations/sec), however, other initial predetermined command velocity Φ₀ may be employed. The control circuit 2510 monitors 10406 the shaft rotation information received from the position sensor 2534 until the I-beam 2514 reaches a target position at the top of the ramp 10006 as shown in FIG. 16B. The predetermined rotation interval period T_(n) is the expected period that the displacement member will take to travel a predetermined distance while traveling at the current set command velocity Φ₀. The deviation between actual rotation period T_(n) and the predetermined rotation period T₀ is due at least in part to external influences acting on the displacement member such as tissue thickness acting on the cutting edge 2509 of the I-beam 2514.

Wth timing information received from the timer/counter circuit 2531 and shaft rotation information received from the position sensor 2534, the control circuit 2510 measures 10408 the time t₀ it takes the displacement member to travel from the reference position 10002 to the target position 10004 after a specified number of shaft rotations (e.g., 12 or 24 rotations). The control circuit 210 sets 10410 the command velocity Φ₁ for the first zone Z₁ based on the measured time t₀. As indicated in Table 1, various defined zones may be defined for staple cartridges of various sizes. Other zones, however, may be defined. The control circuit 2510 sets 10410 the command velocity Φ₁ for the first zone Z₁ by comparing 9412 the measured time t₀ to values stored in memory, such as, for example, stored in a lookup table (LUT). In one example, as indicated in Table 4 generally and in Table 5 by way of specific example, if the time t₀ it takes the I-beam 2514 to travel up the ramp 10006 from the reference positon 10002 to the target position 10004 at 5 rotations/sec is less than 0.9 sec (t₀<0.9 sec), then the command velocity for the first zone Z₁ is set 10414 to FAST (e.g., 30 mm/sec, 71 rotations/sec). Otherwise, if the time t₀ (sec) for the I-beam 2514 to travel up the ramp 10006 from the reference positon 10002 to the target position 10004 at 5 rotations/sec is greater than or equal to 0.9 sec (t₀≥0.9), then the command velocity for the first zone Z₁ is set 10416 to MEDIUM (e.g., 12 mm/sec,29 rotations/sec). Subsequently, the control circuit 2510 checks 10418 for lockout and stops 10420 the motor 2504 if there is a lockout condition. Otherwise, the control circuit enters 10422 the dynamic firing phase as described below in reference to process 10450 in FIG. 22.

FIG. 23 is a logic flow diagram of a process 10450 depicting a control program or logic configuration for controlling command velocity in a dynamic firing stage according to one aspect of this disclosure. With reference also to FIGS. 14 and 16-20, the control circuit 2510 sets 10452 the initial command velocity of the motor 2504 in rotations per second for the first zone Z₁ based on the initial time t₀. as described in reference to the process 10400 in FIG. 21. As the displacement member traverses the staple cartridge 2518, the control circuit 2510 receives the shaft rotation information from the position sensor 2534 and timing information from the timer/counter 2531 circuit and monitors 10454 the number of shaft rotations that represent the position of the displacement member over the predefined zone Z_(n). At the end of the zone Z_(n), the control circuit 2510 measures 10456 the actual time t_(n) the displacement member took to travel from the beginning of the zone Z_(n) to the end of the zone Z_(n) based on a predetermined number of shaft rotations and compares 10458 the actual time t_(n) to a predetermined time for a particular zone as shown generally in Table 2 and by way of specific example in Table 3. The predetermined rotation period T_(n) is the expected rotation period of the displacement member traveling at the current set command velocity Φ_(n) rotations/sec. The deviation between actual rotation period t_(n) and the predetermined rotation period T_(n) is due at least in part to external influences acting on the displacement member such as tissue thickness acting on the cutting edge 2509 of the I-beam 2514.

For example, with reference to Table 3 the time to travel through a zone at a specified command velocity is provided for various dynamic firing zones. For example, if the dynamic firing zone is the zone Z₁ (12 rotations) and t_(n)<0.5 sec, the command velocity for the next zone Z₂ is set to FAST; if 0.5<t_(n)<0.6 sec, the command velocity for the next zone Z₂ is set to MEDIUM; and if t_(n)>0.6 sec, the command velocity for the next zone Z₂ is set to SLOW.

If, however, the dynamic firing zone is an intermediate zone Z₂-Z5 (24 rotations), for example, located between the first zone Z₁ and the last zone Z₆ and if t_(n)<0.9 sec, the command velocity for the next zone Z₂ is set to FAST; if 0.9<t_(n)<1.1 sec, the command velocity for the next zone Z₃-Z5 is set to MEDIUM; and if t_(n)>1.1 sec, the command velocity for the next zone Z₃-Z5 is set to SLOW.

Finally, if the dynamic firing zone is the last measured zone Z5 (24 rotations) and t_(n)<1.0 sec, the command velocity for the final zone Z₆ is set to FAST; if 1.0<t_(n)<1.3 sec, the command velocity for the final zone Z₆ is set to MEDIUM; and if t_(n)>1.3 sec, the command velocity for the final zone Z₆ is set to SLOW. Other parameters may be employed not only to define the dynamic firing zones but also to define the time to travel through a zone at specified command velocity for various dynamic firing zones.

Based on the results of the comparison 10458 algorithm, the control circuit 2510 will continue the process 10450. For example, if the results of the comparison 10458 indicate that the actual velocity (FAST, MEDIUM, SLOW) in the previous zone Z_(n) is the same as the previous command velocity V₁ (FAST, MEDIUM, SLOVV), the control circuit 2510 maintains 10460 the command velocity for the next zone Z_(n+1) the same as the as the previous command velocity. The process 10450 continues to monitor 10454 the number of shaft rotations over the next predefined zone Z_(n+1). At the end of the next zone Z_(n+1), the control circuit 2510 measures 10456 the time t_(n+1) the displacement member took to travel a distance from the beginning of the next zone Z_(n+1) to the end of the next zone Z_(n1) during the predetermined number of shaft rotations and compares 10458 the actual time t_(n+1) to a predetermined time for a particular zone as shown generally in Table 2 and by way of specific example in Table 3. If there are no changes required to the command velocity, the process 10450 until the number of rotations indicates that the displacement member, e.g., the I-beam 2514, has reached the end of stroke 10466 and returns 10468 the displacement member to the reference position 10002.

If the results of the comparison 10458 indicate that the actual velocity (FAST, MEDIUM, SLOW) in the previous zone Z_(n) is different as the previous command velocity Φ₁ (FAST, MEDIUM, SLOVV), the control circuit 2510 resets 10462 or updates the command velocity for the next zone Z_(n+1) according to the algorithm summarized in Tables 2 and 3. If the command speed is reset 10462 or updated to Φ_(new), the control circuit 2510 maintains 10464 the command velocity Φ_(new) for an additional zone Z_(n+2). In other words, at the end of the next zone Z_(n+1), the control circuit 2510 does not evaluate or measure the time. The process 10450 continues to monitor 10454 the number of shaft rotations representative of the position of the displacement member over the next predefined zone Z_(n+1) until the number of rotations indicates that the displacement member, e.g., the I-beam 2514, has reached the end of stroke 10466 and returns 10468 the displacement member to the reference position 10002.

The functions or processes 10400, 10450 described herein may be executed by any of the processing circuits described herein, such as the control circuit 700 described in connection with FIGS. 5-6, the circuits 800, 810, 820 described in FIGS. 7-9, the microcontroller 1104 described in connection with FIGS. 10 and 12, and/or the control circuit 2510 described in FIG. 14.

Aspects of the motorized surgical instrument may be practiced without the specific details disclosed herein. Some aspects have been shown as block diagrams rather than detail. Parts of this disclosure may be presented in terms of instructions that operate on data stored in a computer memory. An algorithm refers to a self-consistent sequence of steps leading to a desired result, where a “step” refers to a manipulation of physical quantities which may take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. These signals may be referred to as bits, values, elements, symbols, characters, terms, numbers. These and similar terms may be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities.

Generally, aspects described herein which can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or any combination thereof can be viewed as being composed of various types of “electrical circuitry.” Consequently, “electrical circuitry” includes electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application specific integrated circuit, electrical circuitry forming a general purpose computing device configured by a computer program (e.g., a general purpose computer or processor configured by a computer program which at least partially carries out processes and/or devices described herein, electrical circuitry forming a memory device (e.g., forms of random access memory), and/or electrical circuitry forming a communications device (e.g., a modem, communications switch, or optical-electrical equipment). These aspects may be implemented in analog or digital form, or combinations thereof.

The foregoing description has set forth aspects of devices and/or processes via the use of block diagrams, flowcharts, and/or examples, which may contain one or more functions and/or operation. Each function and/or operation within such block diagrams, flowcharts, or examples can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In one aspect, several portions of the subject matter described herein may be implemented via Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), digital signal processors (DSPs), Programmable Logic Devices (PLDs), circuits, registers and/or software components, e.g., programs, subroutines, logic and/or combinations of hardware and software components. logic gates, or other integrated formats. Some aspects disclosed herein, in whole or in part, can be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and/or writing the code for the software and or firmware would be well within the skill of one of skill in the art in light of this disclosure.

The mechanisms of the disclosed subject matter are capable of being distributed as a program product in a variety of forms, and that an illustrative aspect of the subject matter described herein applies regardless of the particular type of signal bearing medium used to actually carry out the distribution. Examples of a signal bearing medium include the following: a recordable type medium such as a floppy disk, a hard disk drive, a Compact Disc (CD), a Digital Video Disk (DVD), a digital tape, a computer memory, etc.; and a transmission type medium such as a digital and/or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link (e.g., transmitter, receiver, transmission logic, reception logic, etc.).

The foregoing description of these aspects has been presented for purposes of illustration and description. It is not intended to be exhaustive or limiting to the precise form disclosed. Modifications or variations are possible in light of the above teachings. These aspects were chosen and described in order to illustrate principles and practical application to thereby enable one of ordinary skill in the art to utilize the aspects and with modifications as are suited to the particular use contemplated. It is intended that the claims submitted herewith define the overall scope.

Various aspects of the subject matter described herein are set out in the following numbered examples:

Example 1

A surgical instrument, comprising: a displacement member configured to translate within the surgical instrument over a plurality of predefined zones; a motor comprising a shaft, the motor coupled to the displacement member to translate the displacement member; a control circuit coupled to the motor; a position sensor coupled to the control circuit, the position sensor configured to monitor the rotation of the shaft; a timer circuit coupled to the control circuit, the timer/counter circuit configured to measure elapsed time; wherein the control circuit is configured to: receive, from the position sensor, rotations of the shaft in a current zone defined by a set rotation interval; measure time at a set position of the rotation interval, wherein the measured time is defined as the time taken by the displacement member to traverse the rotation interval based on a predetermined number of shaft rotations; and set a command velocity of the displacement member for a subsequent zone based on the measured time in the current predefined zone.

Example 2

The surgical instrument of Example 1, wherein the control circuit is configured to: determine the set rotation interval in which the displacement member is located, wherein the set rotation interval is defined by a number of rotations of the shaft that result in a linear translation of the displacement member from a beginning position to an ending position; and measure the time when the displacement member reaches the ending position of the rotation interval.

Example 3

The surgical instrument of Example 1 through Example 2, wherein the control circuit is configured to: compare the measured time to a predetermined time stored in a memory coupled to the control circuit; and determine whether to adjust or maintain the command velocity based on the comparison.

Example 4

The surgical instrument of Example 3, wherein the control circuit is configured to maintain the command velocity for the subsequent zone the same as the command velocity of the current zone when the measured time is within a range of predetermined times.

Example 5

The surgical instrument of Example 3 through Example 4, wherein the control circuit is configured to set the command velocity for the subsequent zone different from the command velocity of the current zone when the measured time is outside a range of predetermined times.

Example 6

The surgical instrument of claim 5, wherein the control circuit is configured to skip a time measurement for a subsequent zone when the command velocity is adjusted.

Example 7

The surgical instrument of Example 1 through Example 6, wherein multiple zones are defined for a staple cartridge configured to operate with the surgical instrument.

Example 8

The surgical instrument of claim Example 7, wherein at least two zones have a different length.

Example 9

The surgical instrument of Example 1 through Example 8, further comprising a screw drive system coupled to the shaft of the motor, the screw drive system comprising a lead screw coupled to a nut, wherein the nut is coupled to the displacement member.

Example 10

A surgical instrument, comprising: a displacement member configured to translate within the surgical instrument over a plurality of predefined zones; a motor comprising a shaft, the motor coupled to the displacement member to translate the displacement member; a control circuit coupled to the motor; a position sensor coupled to the control circuit, the position sensor configured to monitor the rotation of the shaft; a timer circuit coupled to the control circuit, the timer/counter circuit configured to measure elapsed time; wherein the control circuit is configured to: receive, from the position sensor, rotations of the shaft in a current zone defined by a predetermined rotation interval; measure time as the displacement member moves from a parked position to a target position based on a predetermined number of shaft rotations; and set a command velocity of the displacement member for a first dynamic zone based on the measured time.

Example 11

The surgical instrument of Example 10, wherein the control circuit is configured to compare the measured time to a predetermined time stored in a memory coupled to the control circuit.

Example 12

The surgical instrument of Example 11, wherein the control circuit is configured to set the command velocity for the initial zone to a first velocity when the measured time is within a first range of times and set the command velocity for the initial zone to a second velocity when the measured time is within a second range of times.

Example 13

The surgical instrument of Example 10 through Example 12, wherein the control circuit is configured to determine a lockout condition and stop the motor.

Example 14

The surgical instrument of Example 10 through Example 13, further comprising a screw drive system coupled to the shaft of the motor, the screw drive system comprising a lead screw coupled to a nut, wherein the nut is coupled to the displacement member.

Example 15

A method of controlling motor velocity in a surgical instrument, the surgical instrument comprising a displacement member configured to translate within the surgical instrument over a plurality of predefined zones, a motor comprising a shaft, the motor coupled to the displacement member to translate the displacement member, a control circuit coupled to the motor, a position sensor coupled to the control circuit, the position sensor configured to monitor the rotation of the shaft, a timer circuit coupled to the control circuit, the timer/counter circuit configured to measure elapsed time, the method comprising: receiving, from a position sensor, rotations of the shaft in a current zone defined by a set rotation interval; measuring, by a timer circuit, a time at a set position of the of the rotation interval, wherein the measured time is defined by the time taken by the displacement member to traverse the rotation interval based on a predetermined number of shaft rotations; and setting, by the control circuit, a command velocity of the displacement member for a subsequent zone based on the measured time in the current zone.

Example 16

The method of Example 15, further comprising: determining, by the control circuit and the timer circuit, the set rotation interval in which the displacement member is located, wherein the set rotation interval is defined by a number of rotations of the shaft that result in a linear translation of the displacement member from a beginning position to an ending position; and measuring, by the control circuit, the time when the displacement member reaches the ending position of the rotation interval.

Example 17

The method of Example 15 through Example 16, further comprising: comparing, by the control circuit, the measured time to a predetermined time stored in a memory coupled to the control circuit; and determining, by the control circuit, whether to adjust or maintain the command velocity based on the comparison.

Example 18

The method of Example 17, further comprising maintaining, by the control circuit, the command velocity for the subsequent zone the same as the command velocity of the current zone when the measured time is within a range of predetermined times.

Example 19

The method of Example 17 through Example 18, further comprising setting, by the control circuit, the command velocity for the subsequent zone different from the command velocity of the current zone when the measured time is outside a range of predetermined times.

Example 20

The method of Example 19, further comprising skipping, by the control circuit, a time measurement for a subsequent zone when the command velocity is adjusted.

Example 21

The method of Example 15 through Example 20, further comprising defining, by the control circuit, multiple zones are defined for a staple cartridge configured to operate with the surgical instrument.

Example 22

The method of Example 21, further comprising defining, by the control circuit, at least two zones having a different length. 

1. A surgical instrument, comprising: a displacement member configured to translate within the surgical instrument over a plurality of predefined zones; a motor comprising a shaft, the motor coupled to the displacement member to translate the displacement member; a control circuit coupled to the motor; a position sensor coupled to the control circuit, the position sensor configured to monitor the rotation of the shaft; a timer circuit coupled to the control circuit, the timer/counter circuit configured to measure elapsed time; wherein the control circuit is configured to: receive, from the position sensor, rotations of the shaft in a current zone defined by a set rotation interval; measure time at a set position of the rotation interval, wherein the measured time is defined as the time taken by the displacement member to traverse the rotation interval based on a predetermined number of shaft rotations; and set a command velocity of the displacement member for a subsequent zone based on the measured time in the current predefined zone.
 2. The surgical instrument of claim 1, wherein the control circuit is configured to: determine the set rotation interval in which the displacement member is located, wherein the set rotation interval is defined by a number of rotations of the shaft that result in a linear translation of the displacement member from a beginning position to an ending position; and measure the time when the displacement member reaches the ending position of the rotation interval.
 3. The surgical instrument of claim 1, wherein the control circuit is configured to: compare the measured time to a predetermined time stored in a memory coupled to the control circuit; and determine whether to adjust or maintain the command velocity based on the comparison.
 4. The surgical instrument of claim 3, wherein the control circuit is configured to maintain the command velocity for the subsequent zone the same as the command velocity of the current zone when the measured time is within a range of predetermined times.
 5. The surgical instrument of claim 3, wherein the control circuit is configured to set the command velocity for the subsequent zone different from the command velocity of the current zone when the measured time is outside a range of predetermined times.
 6. The surgical instrument of claim 5, wherein the control circuit is configured to skip a time measurement for a subsequent zone when the command velocity is adjusted.
 7. The surgical instrument of claim 1, wherein multiple zones are defined for a staple cartridge configured to operate with the surgical instrument.
 8. The surgical instrument of claim 7, wherein at least two zones have a different length.
 9. The surgical instrument of claim 1, further comprising a screw drive system coupled to the shaft of the motor, the screw drive system comprising a lead screw coupled to a nut, wherein the nut is coupled to the displacement member.
 10. A surgical instrument, comprising: a displacement member configured to translate within the surgical instrument over a plurality of predefined zones; a motor comprising a shaft, the motor coupled to the displacement member to translate the displacement member; a control circuit coupled to the motor; a position sensor coupled to the control circuit, the position sensor configured to monitor the rotation of the shaft; a timer circuit coupled to the control circuit, the timer/counter circuit configured to measure elapsed time; wherein the control circuit is configured to: receive, from the position sensor, rotations of the shaft in a current zone defined by a predetermined rotation interval; measure time as the displacement member moves from a parked position to a target position based on a predetermined number of shaft rotations; and set a command velocity of the displacement member for a first dynamic zone based on the measured time.
 11. The surgical instrument of claim 10, wherein the control circuit is configured to compare the measured time to a predetermined time stored in a memory coupled to the control circuit.
 12. The surgical instrument of claim 11, wherein the control circuit is configured to set the command velocity for the initial zone to a first velocity when the measured time is within a first range of times and set the command velocity for the initial zone to a second velocity when the measured time is within a second range of times.
 13. The surgical instrument of claim 10, wherein the control circuit is configured to determine a lockout condition and stop the motor.
 14. The surgical instrument of claim 10, further comprising a screw drive system coupled to the shaft of the motor, the screw drive system comprising a lead screw coupled to a nut, wherein the nut is coupled to the displacement member.
 15. A method of controlling motor velocity in a surgical instrument, the surgical instrument comprising a displacement member configured to translate within the surgical instrument over a plurality of predefined zones, a motor comprising a shaft, the motor coupled to the displacement member to translate the displacement member, a control circuit coupled to the motor, a position sensor coupled to the control circuit, the position sensor configured to monitor the rotation of the shaft, a timer circuit coupled to the control circuit, the timer/counter circuit configured to measure elapsed time, the method comprising: receiving, from a position sensor, rotations of the shaft in a current zone defined by a set rotation interval; measuring, by a timer circuit, a time at a set position of the of the rotation interval, wherein the measured time is defined by the time taken by the displacement member to traverse the rotation interval based on a predetermined number of shaft rotations; and setting, by the control circuit, a command velocity of the displacement member for a subsequent zone based on the measured time in the current zone.
 16. The method of claim 15, further comprising: determining, by the control circuit and the timer circuit, the set rotation interval in which the displacement member is located, wherein the set rotation interval is defined by a number of rotations of the shaft that result in a linear translation of the displacement member from a beginning position to an ending position; and measuring, by the control circuit, the time when the displacement member reaches the ending position of the rotation interval.
 17. The method of claim 15, further comprising: comparing, by the control circuit, the measured time to a predetermined time stored in a memory coupled to the control circuit; and determining, by the control circuit, whether to adjust or maintain the command velocity based on the comparison.
 18. The method of claim 17, further comprising maintaining, by the control circuit, the command velocity for the subsequent zone the same as the command velocity of the current zone when the measured time is within a range of predetermined times.
 19. The method of claim 17, further comprising setting, by the control circuit, the command velocity for the subsequent zone different from the command velocity of the current zone when the measured time is outside a range of predetermined times.
 20. The method of claim 19, further comprising skipping, by the control circuit, a time measurement for a subsequent zone when the command velocity is adjusted.
 21. The method of claim 15, further comprising defining, by the control circuit, multiple zones are defined for a staple cartridge configured to operate with the surgical instrument.
 22. The method of claim 21, further comprising defining, by the control circuit, at least two zones having a different length. 